APROJECT REPORT

ON

GAS & FIRE DETECTION WITH AUTO DIAL UP LOGIC

Submitted

In partial fulfillment

For the award of the degree of

Bachelor of Technology

In Department of Electronics & Communication Engineering

Submitted By:

Ritika Arora (0838131030)Shubhashish Dixit (0838131031)Humaira Anam (0838131409)Rishabh Singh (0838131029)

Department of Electronics & Communication Engineering

Krishna Institute of Management & Technology Moradabad

Rampur Road, NH-24, Moradabad-244001(U.P)

PROJECT REPORTON

GAS & FIRE DETECTION WITH AUTO DIAL UP LOGIC

By

Ritika Arora (0838131030)Shubhashish Dixit (0838131031)Humaira Anam (0838131409)Rishabh Singh (0838131029)

Prof. R.K.YadavMr. Akhilesh SharmaMr. Ajay Kumar

Ms. Sonali Gupta Mr. P.K.RaghavPROJECT GUIDE PROJECT INCHARGE

DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGG.

Krishna Institute of Management & Technology Moradabad

Rampur Road, NH-24, Moradabad-244001(U.P)

DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGG.

CERTIFICATE

This is to certify that the project entitled “GAS & FIRE DETECTION WITH

AUTO DIAL UP LOGIC” has been carried out by RITIKA ARORA,

SHUBHASHISH DIXIT, RISHABH SINGH and HUMAIRA ANAM under

my guidance in partial fulfillment of the degree of Bachelor of Technology in

Electronics & Communication Engineering of Gautam Buddh technical

University Lucknow during the academic year 2011-2012. To the best of my

knowledge and belief this work has not been submitted elsewhere for the

award of any other degree.

Project Incharge Project Guide

Examiner Head of the Department

ACKNOWLEDGEMENT

We would like to place on record my deep sense of gratitude to Prof.

R.K.Yadav, HoD. of Electronics and Communication Engineering, Krishna

Institute of Management & Technology(KIMT), Moradabad, India. Mr.

Akhilesh Sharma, Associate Professor Department of Electronics &

Communication Engineering , KIMT, Moradabad for their generous guidance,

help and useful suggestions.

We express my sincere gratitude to Mr. Ajay Kumar, Senior Lecturer;

Department of Electronics & Communication Engineering, KIMT, Moradabad

Prof. Mr. P.K. Raghav, Senior Lecturer; Ms. Sonali Gupta, Department of

Electronics & Communication Engineering, KIMT, Moradabad, India, for his

stimulating guidance, continuous encouragement and supervision throughout

the course of present work.

We also wish to extend my thanks to Mr. Amit Sharma, Ms. Neha

Goyal, Mr. Amit Chaudhary & all faculty members & college staff for their

insightful comments and constructive suggestions to improve the quality of

this research work.

Ritika Arora (0838131030)

Shubhashish Dixit (0838131031)

Humaira Anam (0838131409)

Rishabh Singh (0838131029)

B.Tech Final YearElectronics & Communication

PAGE INDEX

S. No. CONTENTS Page no.

i Certificate Iii Acknowledgement IIIii List of Tables VIIIiv List of Figures IXv List of Symbols XIvi Abstract XII

1 INTRODUCTION 11.1 General Introduction 1

1.2 Organization Of Project 3

1. 3 Project Statement 7

2 CIRCUIT STRUCTURE 92.1 GENERAL THEORY 92.2 PRIMARY COMPONENTS 92.2.1 AT89C51 MICRO CONTROLLER 102.2.2 SENSOR BOARD 102.3 LED ARRAY 122.4 DRIVER CIRCUIT 122.5 MQ-6 GAS SENSOR 122.5.1 CHARACTERISTICS 122.5.2 APPLICATIONS 122.5.3 STRUCTURE AND CONFIGURATION 132.5.4 BASIC TEST LOOP 132.5.5 CONDITIONS THAT MUST BE AVOIDED 132.6 RESET CIRCUIT 152.7 ALARM 152.8 RELAY 152.9 EXHAUST FAN 162.10 CRYSTAL OSCILLATOR 162.11 AUTO DIALER 16

2.12 POWER SUPPLY 172.13 IC 7805 172.13.1 PIN DIAGRAM 172.13.2 PIN DESCRIPTION:  182.14 DIGITAL VOICE PROCESSOR USING APR 9600

18

2.14.1 MESSAGE MANAGEMENT 192.15 IC 555 AS MONOSTABLE MULTIVIBRATOR

19

2.15.1 MONOSTABLE MULTIVIBRATOR CIRCUIT DETAILS

20

2.15.2 555 IC MONOSTABLE MULTIVIBRATOR OPERATIONS

20

2.15.3 MONOSTABLE MULTIVIBRATOR DESIGN USING 555 TIMER IC

21

2.16 GENERAL FUNCTIONAL DESCRIPTION 212.17 FULL CIRCUIT STRUCTURE & EXPLANATION

22

3 MICROCONTROLLER AT89C51 253.1 AT89C51 MICROCONTROLLER 253.1.1 FEATURES 253.1.2 DESCRIPTION 253.2 ARCHITECTURE OF 8951 FAMILY 263.2.1 PIN DESCRIPTION 263.2.1 VCC 273.2.2 GND 283.2.3 PORT 0 283.2.4 PORT 1 283.2.5 PORT 2 283.2.6 PORT 3 303.2.7 RST 303.2.8 PORT PIN ALTERNATE FUNCTIONS 313.2.9 ALE/PROG 313.2.10 PSEN 323.2.11 EA/VPP 323.2.12 XTAL 1 32

3.2.13 XTAL 2 323.2.14 OSCILLATOR CHARACTERISTICS 323.2.15 IDLE MODE 333.2.16 STATUS OF EXTERNAL PINS DURING IDLE AND POWER-DOWN MODES

34

3.2.17 POWER DOWN MODE 343.2.18 PROGRAMMING THE FLASH 353.2.19 PROGRAM MEMORY LOCK BITS 363.2.20 LOCK BIT PROTECTION MODES 363.3 PROGRAMMING ALGORITHM 373.3.1 DATA POLLING 373.3.2 READY/BUSY 373.3.3 PROGRAM VERIFY 373.3.4 CHIP ERASE 383.3.5 READING THE SIGNATURE BYTES 383.4 PROGRAMMING INTERFACE 383.5 SPECIAL FUNCTION REGISTER (SFR) ADDRESSES

39

3.6 MCS-51 FAMILY INSTRUCTION SET 46

4 COMPUTER AIDED INSTRUCTION 724.1 INTRODUCTION 734.2 CONCEPT OF COMPILER 74

4.3 CONCEPT OF CROSS COMPILER 74

4.3.1 WHY DO WE NEED CROSS COMPILER? 754.4 INSTALLING SDCC 754.5 INSTALLING SiLABS IDE 764.5.1 CONFIGURING SiLABS IDE WITH SDCC 764.6 CREATING A PROJECT 764.6.1 COMPILING A PROJECT 774.6.2 EXECUTING THE PROGRAM ON THE C8051F120

77

4.6.3 ASCII TERMINAL PROGRAMS 784.6.4 IDE FILE LOCATION REQUIREMENT 784.7 PROGRAMMING HINT 78

4.8 8051 PROJECT DEVELOPMENT CYCLE 78

4.9 INSTRUCTION DEFINITION 79

4.10 SOFTWARE LOGIC OF THE PROJECT 86

5 APR9600 RE-RECORDING VOICE IC 915.1 APR 9600 91

5.1.1 FEATURES 91

5.2 GENERAL DESCRIPTION 925.3 FUNCTIONAL DESCRIPTION 925.4 MESSAGE MANAGEMENT 935.4.1 MESSAGE MANAGEMENT GENERAL DESCRIPTION

93

5.4.2 RANDOM ACCESS MODE 955.4.2.1 FUNCTIONAL DESCRIPTION OF RECORDING IN RANDOM ACCESS MODE

95

5.4.2.2 FUNCTIONAL DESCRIPTION OF PLAYBACK RANDOM ACCESS MODE

96

5.4.3 TAPE MODE 965.4.3.1 FUNCTION DESCRIPTION OF RECORDING IN TAPE MODE USING THE AUTO REWIND OPTION

96

5.4.3.2 FUNCTION DESCRIPTION OF PLAYBACK IN TAPE MODE USING AUTO REWIND OPTION

97

5.4.3.3 FUNCTIONAL DESCRIPTION OF RECORDING IN TAPE MODE USING THE NORMAL OPTION

98

5.4.3.4 FUNCTIONAL DESCRIPTION OF PLAYBACK IN TAPE MODE USING THE NORMAL OPTION

99

5.5 MICROPROCESSOR CONTROLLED MESSAGE MANAGEMENT

100

5.6 SIGNAL STORAGE 1015.7 SAMPLING RATE & VOICE QUALITY 1015.8 AUTOMATIC GAIN CONTROL (AGC) 102

5.9 SAMPLING APPLICATION 102

5.10 FIGURES OF MODES 103

5.11 PIN DESCRIPTION 1065.12 ELECTRICAL CHARACTERISTICS 1085.13 APPLICATION TIPS 110

TIPS FOR BETTER SOUND REPLAY QUALITY

6 CONCLUSION AND FUTURE ENHANCEMENT

111

6.1 CONCLUSION 1116.2 RESULT 1126.3 LIMITATIONS 1126.4 FUTURE SCOPE 113

BIBLIOGRAPHY 115

LIST OF TABLES

Tables Page No.

Table 2.1 Pin Description of IC 7805 18Table 3.1 Pin Diagram of AT89C51 30Table 3.2 Port 3 Functions 31Table 3.3 Status of External Pins during Idle and Power-Down

Modes34

Table 3.4 Flash Programming Mode Signature Codes 35Table 3.5 Lock Bit Protection Modes 36Table 3.6 Signature Bytes 38Table 3.7 SFR Addresses 39Table 3.8 Modes of Operation 40Table 3.9 PSW Register Details 41Table 3.10 PCON Register 42Table 3.11 Baud Rate Comparison for XTAL = 11.0592 MHZ 42Table 3.12 TCON Register 43Table 3.13 SCON Register 43Table 3.14 Modes of SCON Register 44Table 3.15 TMOD Register 44Table 3.16 Modes of TMOD 44Table 3.17 IE Register 45Table 3.18 IP Register 45Table 3.19 T2CON Register 46Table 5.1 Mode selection 95Table 5.2 Input Bandwidth & Duration 101Table 5.3 Pin Description of APR 9600 108Table 5.4 Absolute Maximum Ratings 109Table 5.5 DC Characteristics 109Table 5.6 Analog Characteristics 109

LIST OF FIGURES

Figures Page No.

Fig 2.1 Gas & Fire Sensor using 555 IC 11Fig 2.2 Structure & Configuration of Gas Sensor MQ-6 13Fig 2.3 Basic Test Loop 14Fig 2.4 Basic Relay Block with Handsfree 16Fig 2.5 Pin Diagram of IC 7805 17Fig 2.6 555-Timer-Monostable-Multivibrator 20Fig 2.7 555 Monostable-Multivibrator-Operation 20Fig 2.8 Complete Circuit structure of Gas & Heat Sensor with auto dial up logic

24

Fig 3.1 Basic Architecture of AT89C51 Microcontroller 26Fig 3.2 Pin Diagram of Micro controller 8951 27Fig 3.3 Oscillator connection 33Figure 3.4 External Clock Drive Configuration 34Fig 3.5 TMOD Register 39Fig 3.6 PSW Register 41Fig 3.8 Arithmetic Operation 47Fig 3.9 Logic Operation 493.10 Data Transfer Operation 49Fig 3.11 Boolean Manipulation & Program & Machine Control Operation

50

Fig 4.1 Load New File in 8051 IDE 82Fig 4.2 Auto Dial Up Coding 83Fig 4.3 8951 Selection 84Fig 4.4 Loading Flash Buffer 85Fig 4.5 Gas Sensor with MCU 88Fig 4.6 Gas Sensor with MCU 89Fig 5.1 Pin Diagram of APR 9600 IC 93Figure 5.2 APR9600 Block Diagram 94Fig 5.3 APR9600 Experimental board 100Figure 5.4 Tape Mode, Normal Option 103Figure 5.5 Tape Mode, Auto Rewind Option 104

Figure 5.6 Random Access Mode 105

LIST OF SYMBOLS

Symbols MeaningLED Light Emitting DiodeIC Integrated ChipGSM Global System ModulePC Personal ComputerDIP  Dual In-line PackageRAM Random Access MemoryROM Read Only MemoryI/O Input OutputVCC Level 1 VoltageGND GroundXTAL CrystalPpm Parts per millionMCU Micro Controller UnitAPR Auto Pre RecordingAGC Automatic Gain ControlCMOS Complementary Metal Oxide SemiconductorMHz Mega HertzAC Alternating CurrentDC Direct CurrentUART Universal Asynchronous Receiver-TransmitterCPU Central Processing UnitBIT Binary UnitCLK ClockANA Analogue

ABSTRACT

Security is primary concern for everyone. This Project describes a design of effective security alarm system that can monitor an industry with different sensors. Gas detection and fire detection can be monitored by the status of each individual sensor and is indicated with an LED, Buzzer Voice Recording & Playback Device and dial up logic. These all shows whether the sensor has been activated and whether the wiring to the sensor is in order. In this project we show that how we use the telephone as a electronics eye. With the help of any phone we can know the position of the house. In this logic we attach some sensor with the telephone and if there is any mishappening at home then telephone is automatic on and then circuit press the redial button of the telephone and then telephone dial the pre-dialed number and sense the voice message to the received end.

The detection alarm is built around the AT89C51 microcontroller from Atmel. This microcontroller provides all the functionality of the detection alarm. It also takes care of filtering of the signals at the inputs. A fire sensor can be connected to the gas sensor alarm. These sensors need to have their contacts closed when in the inactive state (i.e. normally closed). In addition, each sensor needs to have its tamper connection wired as well. A power supply voltage of +5 VDC is available for each sensor at the corresponding wiring terminals. LEDs indicate the status of the corresponding sensors. When the alarm has been activated, the LED of the sensor that caused the alarm will light up and pre recorded message starts to play.

The uniqueness of this project is not only alerting the neighbors by siren, it also dials a mobile number which is already programmed into the system. A mobile number or a land line number can be programmed into the system. As this system works on existing telephone line, it can dial the number even the subscriber is out of station.

This project uses regulated 5V, 500mA power supply. 7805 three terminal voltage regulator is used for voltage regulation. Bridge type full wave rectifier is used to rectify the ac output of secondary of 230/12V step down transformer.

CHAPTER - 1 INTRODUCTION

1.1 GENERAL INTRODUCTIONEngineering is not only a theoretical study but it is a implementation of

all we study for creating something new and making things more easy and useful through practical study. It is an art which can be gained with systematic study, observation and practice. In the college curriculum we usually get the theoretical knowledge of industries, and a little bit of implementation knowledge that how it is works? But how can we prove our practical knowledge to increase the productivity or efficiency of the industry????

Don’t take the chance of becoming victim of carelessness, which is often accompanied by serious accident. Protect our family and valuables with this microcontroller based security system that will let us rest our head knowing that there is anything like gas leakage or fire existing into our home.The motivation is to facilitate the users to know the state of their homes having ubiquitous access. The system provides availability due to development of a low cost system. This system is low cost but very useful for users to know their home state wherever are located. Home security has been a major issue where temperature starts raising day by day and everybody wants to take proper measures to prevent intrusion. There was need to prevent fires and gas leaks no matter when they are in the house or outside. By using GSM technology via Dial-Up logic we can help users to supervise their home against intruders, gas leak and fire only at one product with a low cost.

The security is what a person expects from a home, this project was designed keeping this particular aspect in mind. The security system is made fool proof to the maximum extent possible. In this project we make use of a microcontroller as the main controller to control the input and the output that reach the controller. There is a large scope in the future enhancements that can be provided along with this project like actuating a fire detection alarm or sensing a leakage of gas etc.

Generally in any industry, there are several blocks and there is an administrative block which controls all blocks. If any problem is created in any one of the blocks, at first the persons in that particular block has to inform to the administrative block and then the action will be taken. So if we consider a fire accident in any one of the blocks the person on that incident generally they makes a call to the administrative block or security block as took over and they has to call the ambulance, fire station etc. It will be a long time process, so in the mean the damage may increase in gigantic extent. The most basic fire protection methods include fire prevention, detection and control. Buildings

should be constructed using fire rated walls, doors, ceilings and floors. The use of combustible materials in interior furnishing should be kept to a minimum. There are several types of detection devices. Automatic fire detection systems, when combined with other elements of an emergency response and evacuation plan, can significantly reduce property damage, personal injuries, and loss of life from fire in the work place. Their main function is to quickly identify a developing fire and alert building occupants and emergency response personnel before extensive damage transpire. Automatic fire detection systems do this by using electronic sensors to detect the smoke, heat or flames and providing an early warning. Heat detectors which respond to heat generated in the flame stage of a fire and smoke detectors which respond to the particles of cumbers ion produced in a fire.

A fire alarm control panel, normally referred to as a panel within the active fire protection industry is central control device for detecting, reporting and acting on occurrences of fire with in a building. There are two types of panel's fallen conventional panels and analogue addressable panels. In a conventional panel, fire detection devices including, but not limited to smoke detectors, heat detectors and manual call points are joined up with a number connected to the circuit. When a device on the circuit is activated the panel recognizes an alarm on that circuit and could be setup to take a number of actions including directly calling the fire department via an alarm transportation system. An addressable panel is a more modern type of panel and has a greater flexibility than a conventional panel. An addressable panel has a number of loops where a number of devices are to be connected, each with its own address. Bad experiences with early systems have left the police reluctant to allow domestic security system to call for assistance directly, except on high risk situations. Security systems can now be configured to call telephones in the event of an alarm so that the occupants are nominated care takers can be alerted before calling the police.

Business and industry today requires security systems that are the fact of life. Your company simply must have them to protect your employees, your equipment and sky scrapers themselves. There is only one thing more important than the selection of the security systems to protect your facilities. That is why you should consider reliable fire equipment for your security system requirements. Security and fire protection are closely related to energy management in so far as they present tractable goals for automated systems. It has been considered relatively easy for machine based systems to recognize anomalous activity around the home which could be interpreted as possible security breaches, accidents or fires. Fire damage, however can be permanent and involves the entire life of human. Much can be done to minimize the chance of a fire stating or spreading. Progress in fire technologies has been substantial over last decade due to advances in sensor, microelectronics and

information technologies, as well as a greater understanding of fire physics. This paper provides a review of progress in fire detection technologies over the last decades some problems & a future research efforts related to current fire detection technologies are discussed.

1.2 ORGANIZATION OF PROJECTThis project design makes use of 8951 microcontroller for interfacing to

various hardware interfaces. Technology today is seeing its heights in all the areas, especially in the area of Embedded Systems. It is true that every electronic gadget that is used in daily life right from a PC keyboard to a refrigerator is an Embedded System. These all itself shows how vastly the technology is expanding. This design is also one of such application.

The Micro controller which we are using in our Project is 8951 manufactured by ATMEL Corporation. It is a 40 pin DIP plastic packaging CMOS technology having inbuilt ROM of 4K, RAM of 128 bytes, 32 I/O pins (of which two I/O pins P3.0 and P3.1 can be used for serial communication i.e., pins 10 & 11), 2 Timers and 6 Interrupts. It has an inbuilt Crystal Oscillator generating 12 MHz connected to 18 & 19 pins which is indicated for speed of 8051. When the Micro Controller is at initial condition or got switched ON, the I/O pins are at high indicating as input pins. The 40 th pin is given Vcc supply of +5V and 20th to GND.

Gas sensors work by detecting amounts of specific gases in ppm, or parts per million. Ppm is a unit of concentration in the immediate surrounding area. You can calculate percent from ppm by dividing the ppm by 1,000,000 and multiplying by 100. So if you can detect 800ppm of oxygen in the air, the air is 8% oxygen. (Our atmosphere is more than 20% Oxygen, but this is just an example). The sensing element for gas sensors is coated with a metal oxide, and the Figaro models interested in use Tin oxide specifically (SnO2). When the heating element receives power, the SnO2 becomes oxidized and donates electrons to the Oxygen yielding positively charged SnO2 molecules on the coating of the sensing element. This situation causes a barrier to electron flow, increasing resistance of the sensor. When a deoxidizing gas is introduced in the equation (such as ethanol, or C2H5OH), the amount of available oxygen decreases. This means that there is less oxygen to accept the donor electrons from the SnO2 coating, which reduces the resistance of the sensor due to the SnO2 not being as positively charged. Reduce resistance cause flow of current and thus output signal goes high.

Security is the condition of being protected against danger or loss. In the general sense, security is a concept similar to safety. The nuance between the two is an added emphasis on being protected from dangers that originate from outside. Individuals or actions that encroach upon the condition of protection

are responsible for the breach of security. The word "security" in general usage is synonymous with "safety," but as a technical term "security" means that something not only is secure but that it has been secured. One of the best options for providing good security is by using a technology named EMBEDDED SYSTEMS. When people become more and more attach importance to the quality of life, the security and service is important. Security has arguably become the prime mover of global politics today. It is the basic common denominator for any successful society all over the world. Now days the security system can identify potential hazards to protect human. A typical intelligent security system consists of intruders, fire, gas, environment sensors and more variety sensors to be installed.

Monitoring of the security system ensures an effective response to an electronic activation or in times of personal duress. The response opinions are customized to suit the individual risk security requirements in cost effective manner. Monitoring is done through a telephone line and depending on the security task it will involve a basic digital dialer or a security interface. The most common method of monitoring is achieved via the basic dialer. This is for low to medium security risk and is connected to the existing telephone line through a special socket. The system will communicate when an alarm condition needs to be reported or when a call is made to test the system. This test is made as often as required to ensure more or less security. The security interface provides the same service but it involves a scanning of the existing telephone line by the telephone company to ensure greater security. Should the telephone line be damaged accidentally or on purpose the monitoring station will detect the alarm condition within seconds????

Nowadays trend in network communication leads to replacing the cables, providing mobility and freedom of movement for the user’s. The utilization of wireless techniques has spread its scope on to different application fields. One of such spheres is industry with the addition of wireless connectivity to most embedded designs; zones of security will be needed around each critical system MCU, in addition to the one traditionally surrounding the gateway to the broader network.

(Source: Atmel)."Beyond the huge cost savings incurred by eliminating wires, are the continuing costs in maintenance that will be eliminated, as well as the flexibility that gives the manufacturer who wants to recognize the factory floor, add new systems and eliminate others. No wires to connect and disconnect eliminates a lot of costs and will make the factory floor a much more dynamic environment".

This Project describes a design of effective security alarm system that can monitor an industry with two different sensors. Fire accident and gas detection can be monitored by the status of each individual sensor and is indicated with an LED. This LED shows whether the sensor has been activated

and whether the wiring to the sensor is in order. Obviously, this alarm also has an input to 'arm' the alarm to control a siren and Auto dialing system.

The gas sensor and fire sensor alarm is built around the AT89C51 micro controller from Atmel. This micro controller provides all the functionality of the detection alarm. It also takes care of filtering of the signals at the inputs. Only after an input has remained unchanged for 30 milliseconds, is this new signal level passed on for processing by the micro controller program. This time can be varied by adopting small changes in the source code.

A maximum of 8 sensors can be connected to the 8951but here we only connected 2 sensors. These sensors need to have their contacts closed when in the inactive state (i.e. Normally Closed). In addition, each sensor needs to have its tamper connection wired as well. A power supply voltage of +5 VDC is available for each sensor at the corresponding wiring terminals. LEDs indicate the status of the corresponding sensors. When the alarm has been activated, the LED of the sensor that caused the alarm will light up, or flash in the event of a cable failure.

When the alarm is armed, the LED 'alarm armed' will flash during the exit-delay. After the exit-delay, the LED will light continuously. The LED 'alarm triggered LED' flashes during the entry-delay and will turn on continuously once an actual alarm has been generated. 'Alarm triggered LED’ turns off only when the alarm is switched off with key switch Sw1. When an alarm has taken place, it can be determined afterwards which sensor (or tamper input) caused the alarm to trigger. The LED 'tamper' lights up when the tamper input is opened. This LED will also continue to be on until the alarm is switched off.

The uniqueness of this project is not only alerting the neighbors by siren, it also redials a mobile number which is already in dial list. A mobile number or a land line number can be fixed for it. As this system works on existing mobile, it can dial the number even the subscriber is out of station. Another important feature that is connected to circuit is Single-Chip Voice Recording & Playback Device. An IC APR9600 is implemented for it. The APR9600 device offers true single-chip voice recording, non-volatile storage, and playback capability for 40 to 60 seconds. The device supports both random and sequential access of multiple messages. Sample rates are user-selectable, allowing designers to customize their design for unique quality and storage time needs. Integrated output amplifier, microphone amplifier, and AGC circuits greatly simplify system design. The device is ideal for use in portable voice recorders, toys, and many other consumer and industrial applications. APLUS integrated achieves these high levels of storage capability by using its proprietary analog/multilevel storage technology implemented in an advanced Flash non-volatile memory process, where each memory cell can store 256 voltage levels. This technology enables the

APR9600 device to reproduce voice signals in their natural form. It eliminates the need for encoding and compression, which often introduce distortion.

This project uses regulated 5V, 500mA power supply. 7805 three terminal voltage regulator is used for voltage regulation. Bridge type full wave rectifier is used to rectify the ac output of secondary of 230/12V step down transformer.

As the operation of microcontroller-based system is inherently based on the stored program control concept, the software plays a very crucial role. The relationship between the hardware and software is similar to the relation between body and soul. One has not a meaningful existence without the other. The hardware is the body, which is used as the medium of software. In order to develop the software for microcontroller based system, one must acquire knowledge about the set of instructions which are used as a building blocks in writing a program and learn the art of program that is the tools and techniques of putting instructions together in a logic manner to form a program implementing the desired operations. The 8051 IDE Assembler + Compiler development tools are designed to solve the complex problems facing embedded software developed.

1. 3 PROJECT STATEMENTNowadays, most couples leave for work early in the morning and get

back only in the evening. Most people also have to travel to other cities for their work. When they are away, their house is empty. Therefore case like leakage of LPG and short circuitry fire or else is easy to occur because the home owners are not in the house. Our Country India has many such cases and still going ascending day by day. The based solution is to develop home security system using a wireless to keeps your house safe from such accidents and enables you to work in peace.

Based on the events above, the project can be developing to make our home secure and safe. We never anxious and worried anymore even we leave the house. So this project is to design and develop a home security system that can provide security against gas leak, fire and other emergency situation by alarm via calling to the home owner as there is something suspicious at home. Today there are a many wireless home security alarm system available in the market. Some are designed for very high security level protection and some are basic type. Most of the alarm systems are very expensive and therefore not affordable by poor or middle class families. Some systems which cheaper in cost do not provide reliable features like status checking. To provide the public with a cost effective wireless security system, it is important to design a low cost system with advanced features which ease the residents' life and benefits the public and also will decrease the accident rate of India. Besides that, to

develop the system that can monitor gas leakage and fire detector including control appliances in our home is a good matter. It is important because the system can be help people through the realization of fully automated home protections. So this project wills develops and design the home security system that can control the lamp in the house.

CHAPTER – 2 CIRCUIT STRUCTURE

This chapter deals with the general introduction of all the components used in this project. So we can have a general idea about all the components. We also have some computer aided instructions and their operation which will discussed in next chapter.

2.1 GENERAL THEORYAn embedded system can be defined as a computing device that does

a specific focused job. Appliances such as the air-conditioner, VCD player, DVD player, printer, fax machine, mobile phone etc. are examples of embedded systems. Each of these appliances will have a processor and special hardware to meet the specific requirement of the application along with the embedded software that is executed by the processor for meeting that specific requirement. The embedded software is also called “firm ware”. The desktop/laptop computer is a general purpose computer. You can use it for a variety of applications such as playing games, word processing, accounting, software development and so on. In contrast, the software in the embedded systems is always fixed listed below:

Embedded system does a very specific task; they cannot be programmed to do different things. Embedded systems have very limited resources, particularly the memory. Generally, they do not have secondary storage devices such as the CDROM or the floppy disk. Embedded systems have to work against some deadlines. A specific job has to be completed within a specific time. In some embedded systems, called real-time systems, the deadlines are stringent. Missing a deadline may cause a catastrophe-loss of life or damage to property. Embedded systems are constrained for power. As many embedded systems operate through a battery, the power consumption has to be very low.

2.2 PRIMARY COMPONENTSPrimary components of the electro circuit are as follows which will describe

serially.

AT89C51 Micro controller Gas & Fire Sensor board LED array 555 IC

Reset circuit ALARM Relays Crystal oscillator Auto dialer Power supply

2.2.1 AT89C51 MICRO CONTROLLER8051 is one of the most popular micro controllers in use today. Many

derivative micro controller have since been developed that are based on and compatible with the 8051.Thus, the ability to program an 8051 is an important skill for anyone who plans to develop products that will take advantage of micro controller. P89C51 is same as the INTEL 8051 except that 89C51 has internal flash ROM, which can be programmed more than 1000 times.

The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash Programmable and Erasable Read Only Memory (PROM). The device is manufactured using Atmel’s high density nonvolatile memory technology and is compatible with the industry standard MCS-51™ instruction set and pin out. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the ATMEL AT89C51 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications. The AT89C51 provides the following standard features: 4K bytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, five vector two-level interrupt architecture, a full duplex serial port, and on-chip oscillator and clock circuitry.[2][9]

2.2.2 SENSOR BOARDThe different sensors used in this project are as follows: Gas Sensor Fire & Heat Sensor

In this sensor unit we connect 2 sensors, now it is our choice how many sensors’ we use.

In the fire sensor we use bimetallic plates to sense fire, when fire touch the bimetallic plates then plates join together and immediate provide a signal to the controller. Fire sensor is attached to the IC 555. Here IC 555 work as a

mono stable timer and output signal is available on the pin 3 this signal is connected to the microcontroller .When fire is on then sensor detect the logic and immediate provide a signal to the controller.

Gas sensor is a special sensor when gas sensor sense the gas then gas sensor again provides a small signal to the microcontroller via IC 555.In the gas sensor interface we use gas sensor as a input logic. We attach one IC 555 as with this sensor. Here IC 555 works as a monostable multivibrator timer. Sensor output is connected to the IC 555 pin no 2 via NPN transistor. Pin no 2 is a negative triggered IC. When sensor activate then positive output is available and this positive output is converted into negative with the help of the NPN transistor. Output of the NPN transistor is now connected to the pin no 2 of the IC 555. Pin no 4 and 8 of the IC 555 is connected to the positive supply. Pin no 1 is connected to the ground pin. Pin no 7 is the output pin. Pin no 6 and 7 is the time constant pin. Pin no 6 and 7 provide a time constant option. When IC 555 works then output is available on the pin no 3. Now this output is switching by the further NPN transistor. One LED is also connected to the transistor circuit. Output of the NPN transistor is available on the collector point. This output from the collector of NPN is now connected to the microcontroller pin no 1 which is port p1.0. Pin no 40 of the controller is connected to the positive supply. We supply a 5 volt for supply.

These sensors’ firstly connected with the monostable circuit and then connected to the microcontroller interface. In the monostable circuit we use IC 555 as a monostable circuit.

Fig 2.1 Gas & Fire Sensor using 555 IC

Output of the IC 555 is connected to the microcontroller circuit. Here we use ATMEL microcontroller. In the ATMEL series many controllers are available and the entire controllers are compatible with each other. Here we use IC 89s51 or 89c2051 controller. IC 89c2051 is a 20 pin controller and 89c51 is a 40 pin controller. So we use AT89c51 microcontroller for multi function.

2.3 LED ARRAYLight-emitting diodes are elements for light signalization in

electronics. They are manufactured in different shapes, colors and sizes. For their low price, low consumption and simple use, they have almost completely pushed aside other light sources- bulbs at first place. They perform similar to common diodes with the difference that they emit light when current flows through them.

2.4 DRIVER CIRCUITA driver circuit is used for driving the LEDs. An open-drain output can

drive an LED. If either of the input to the driver circuit is LOW, the corresponding n-channel transistors are off and the LED is off. When both the inputs are High, both transistors are ON. Then the output is LOW.

2.5 MQ-6 GAS SENSORSensitive material of MQ-6 gas sensor is SnO2, which with lower

conductivity in clean air. When the target combustible gas exist, the sensor’s conductivity is higher along with the gas concentration rising. Please use simple electro circuit, Convert change of conductivity to correspond output signal of gas concentration. MQ-6 gas sensor has high sensitivity to Propane, Butane and LPG, also response to Natural gas. The sensor could be used to detect different combustible gas, especially Methane; it is with low cost and suitable for different application.[7]

2.5.1 CHARACTERISTICS Good sensitivity to Combustible gas in wide range High sensitivity to Propane, Butane and LPG Long life and low cost Simple drive circuit

2.5.2 APPLICATIONS Domestic gas leakage detector Industrial Combustible gas detector

Portable gas detector

2.5.3 STRUCTURE AND CONFIGURATIONStructure and configuration of MQ-6 gas sensor is shown as Fig. 3,

sensor composed by micro AL2O3 ceramic tube, Tin Dioxide (SnO2) sensitive layer, measuring electrode and heater are fixed into a crust made by plastic and stainless steel net. The heater provides necessary work conditions for work of sensitive components. The enveloped MQ-4 has 6 pin, 4 of them are used to fetch signals, and other 2 are used for providing heating current.

Fig 2.2 Structure & Configuration of Gas Sensor MQ-6

2.5.4 BASIC TEST LOOPBelow fig 2.3 is basic test circuit of the sensor. The sensor needs to be put 2

voltage, heater voltage (VH) and test voltage (VC). VH used to supply certified working temperature to the sensor, while VC used to detect voltage (VRL) on load resistance (RL) whom is in series with sensor. The sensor has light polarity, VC need DC power. VC and VH could use same power circuit with precondition to assure performance of sensor. In order to make the sensor with better performance, suitable RL value is needed.

Power of Sensitivity body (Ps): PS=Vc2×Rs/ (RS+RL) 2

Resistance of Sensor (RS): RS = (VCC/VRL-1) × RL.

2.5.5 CONDITIONS THAT MUST BE AVOIDED Water CondensationIndoor conditions, slight water condensation will affect sensors

performance lightly. However, if water condensation on sensors surface and keep a certain period, sensor’ sensitivity will be decreased.

Fig 2.3 Basic Test Loop

Used in high gas concentrationNo matter the sensor is electrified or not, if long time placed in high gas

concentration, if will affect sensors characteristic. Long time storageThe sensors resistance produce reversible drift if it’s stored for long time

without electrify, this drift is related with storage conditions. Sensors should be stored in airproof without silicon jell bag with clean air. For the sensors with long time storage but no electrify, they need long aging time for stability before using.

Long time exposed to adverse environmentNo matter the sensors electrified or not, if exposed to adverse

environment for long time, such as high humidity, high temperature, or high pollution etc, it will affect the sensors performance badly.

VibrationContinual vibration will result in sensors down-lead response then

rupture. In transportation or assembling line, pneumatic screwdriver/ultrasonic welding machine can lead this vibration.

ConcussionIf sensors meet strong concussion, it may lead its lead wire disconnected. UsageFor sensor, handmade welding is optimal way. If use wave crest welding

should meet the following conditions:

Soldering flux: Rosin soldering flux contains least chlorine Speed: 1-2 Meter/ Minute

Warm-up temperature：100±20℃

Welding temperature：250±10℃ 1 time pass wave crest welding machine.

If disobey the above using terms, sensors sensitivity will be reduced.

2.6 RESET CIRCUITFor proper system operation, the hardware design of a state machine

should ensure that it enters a known initial state on power-up. Most systems have a RESET signal that is asserted during power-up. If a state machine is built using discrete flip-flops with asynchronous preset and clear inputs, the RESET signal can be applied to these inputs to force the machine in to the desired initial state.

2.7 ALARMAn ALARM is used to indicate detection in home as well as in industry.

When Gas is detected by the heat detector and the buzzer is activated. Same as in case of heat or fire, when heat is detected by the heat detector and the buzzer is activated.

2.8 RELAYA relay is an electrically controllable switch widely used in industrial

controls, automobiles and appliances. A relays are widely used electronics circuits as remote control LED mechanical switches turn a sequence of events ON and OFF. Relays are provided some mechanical contacts and with their help they control operation of other circuits. The terminology of both relays and switches is identical that is similar to switches. Output of the controller is connected to the relay driver circuit. Relay driver circuit basically provide a ON OFF signal in single pulse. We connect these pulses to the hands free of the cell phone. When hands free of the telephone is activate through the microcontroller then phone is automatic on and last redial number is dialed. When last number is redialed then after call voice processor is on automatically and voice signal is transfer to the mobile phone through mike.

To drive a relay we use two transistor circuits. One is NPN and second is PNP transistor. Output from the controller is connected to the base point of the PNP transistor through 1k ohm resistor. Emitter of the PNP transistor is connected to the positive supply. Collector is connected to the base of the NPN transistor. Collector of the NPN transistor is connected to the relay coil. This relay coil presses the hands free coil and redials the last number directly. User can treat it as a warning message to go to home or industry if owner is out of station. Once the call is activate then sound is transfer from the voice processor to the mobile phone. Here we use IC APR 9600. With the help of this IC we produce up to 6 sounds and it is possible to send a different sound on different

application with the help of the mobile phone. When the relay is on and activates the last number redial the after few second voice processor pin is on and play a voice message this message is transfer to the phone automatically.

Fig 2.4 Basic Relay Block with Handsfree

2.9 EXHAUST FANThere is also an exhaust fan installed in the circuitry, which is activated

by the IC 555 monostable IC. If there is too much concentration of gas in premises, and gas sensor detects it, microcontroller also give command to activate exhaust fan so that the room get reduce concentration of the Gas before the concerned authorities arrive there. However in case of Fire/Heat Sensor, it will remain in its idle state of OFF.

2.10 CRYSTAL OSCILLATORTo stabilize the frequency of the internal oscillator we have to add

an external oscillator of frequency 11.0592 MHZ. Certain crystalline materials, namely Rochelle salt, quartz and tourmaline exhibit the piezoelectric effects are called piezoelectric crystals. Of the various piezoelectric crystals, quartz is more commonly used because it is inexpensive and readily available in nature.

2.11 AUTO DIALERA telephone is used in the system in order to convey the alert message to

the concerned authorities. In the system, telephone plays a vital role, because even if the alarm is not heard by anyone present in the vicinity of the system, the message can be intimated to the required destination by the number which

is already stored in it. This helps to improve out security level by use of electro circuit.2.12 POWER SUPPLY

The input to the circuit is applied from the regulated power supply. The AC input i.e., 230V from the mains supply is step down by the transformer to 12V and is fed to a rectifier. The output obtained from the rectifier is a pulsating DC voltage. So in order to get a pure DC voltage, the output voltage from the rectifier is fed to a filter to remove any AC components present even after rectification. Now, this voltage is given to a voltage regulator 7805 to obtain a pure constant dc voltage.

2.13 IC 78057805 is a voltage regulator integrated circuit. It is a member of 78xx

series of fixed linear voltage regulator ICs. The voltage source in a circuit may have fluctuations and would not give the fixed voltage output. The voltage regulator IC maintains the output voltage at a constant value. The xx in 78xx indicates the fixed output voltage it is designed to provide. 7805 provides +5V regulated power supply. Capacitors of suitable values can be connected at input and output pins depending upon the respective voltage levels.[8] 2.13.1 PIN DIAGRAM

Fig 2.5 Pin Diagram of IC 7805

2.13.2 PIN DESCRIPTION: Table 2.1 shows the pin description of IC 7805.

Pin No

Function Name

1 Input voltage (5V-18V) Input

2 Ground (0V) Ground

3 Regulated output; 5V (4.8V-5.2V) Output

Table 2.1 Pin Description of IC 7805

2.14 DIGITAL VOICE PROCESSOR USING APR 9600Digital voice recording chips with different features and coding

technology for speech compression and processing are available on the market from a number of semiconductor manufacture. Advanced chips such as Texas instrument TMS320C31 can implement various voice processing algorithms including code-excited linear prediction, adaptive differential pulse code modulation. A law (specified by California Council for international trade), micro law (specified by Bell telephone) and vector sum excited linear prediction. On the other hand APR 9600 single chip voice recorder and playback device from APLUS integrated circuits makes use of a proprietary analogue storage technique implemented using flash non-volatile memory process in which each cell is capable of storing up to 256 voltage levels. This technology enables the APR9600 to reproduce voice signals in the natural form. The APR 9600 is a good stand lone voice recorder or playback IC with non volatile storage and playback capability from 5 to 60 seconds. It can record and play multiple messages at random or in sequential mode. The user can select sample rates with consequent quality and recording time trade off. Microphone amplifier, automatic gain control (AGC) circuits, internal anti aliasing filter, integrated output amplifier and message management are some of the features of the APR 9600. Complete chip management is accomplished through the device control and message control blocks. Voice signal from the microphone is fed into the chip through a differential amplifier. It is further amplified by connecting Analogue-Out (pin 21) to Analogue in (pin 20) via an external DC blocking capacitor C1. A bias signal is applied to the microphone and to save power during playback, the ground return of this bias network can be connected to the normally open side of the record switch. Both Mike in and Mike Ref (pins 18 and 19) must be coupled to the microphone network through capacitors. Recording signal from the external source can also be fed

directly into the chip using Ana-In (pin 20), but the connection between Ana-in ( pin 20) and Ana-out (pin 21) is still required for playback. An internal anti-aliasing filter automatically adjusts its response according to the sampling frequency selected. Then the signal is processed into the memory array through a combination of the sample and hold circuits and analogue read/write circuit. The incoming voice signals are sampled and the instantaneous voltage samples are stored in the non-volatile flash memory cells in the 8 bit binary encoded format. During playback, the stored signals are retrieved from the memory, smoothed to form a continuous signal level at the speaker terminals SP+ and SP- ( pins 14 and 15 respectively) is at about 12mw power into 16 ohm impedance. The output from pin 14 (SP+) is further amplified by the low power amplifier using LM386 (IC2) as shown in the figure. The recorded message is reproduced into speaker LS1. An internal oscillator provides sampling clock to the APR 9600. The frequency of the oscillator and sampling rate depend on the value of resistor R12 connected across the OSCR (pin 7) of the chip and the ground.[6][12]

2.14.1 MESSAGE MANAGEMENTThe APR9600 chip supports the following message modes. Random

access mode with 2, 4, 8 message within the total recording time. Tape mode with two options: Auto rewind and Normal operation. The modes are defined by pins 24, 25 and 9 cannot be mixed. An important feature of the APR9600 chip is indication of changes in the device status through beeps superimposed on the device output: for example, the start of recording is indicated by a beep, so the person can now start speaking into the microphone. This feature is enabled by making pin 11 high.

2.15 IC 555 AS MONOSTABLE MULTIVIBRATORA monostable multivibrator (MMV) often called a one-shot

multivibrator, is a pulse generator circuit in which the duration of the pulse is determined by the R-C network, connected externally to the  555 timer . In such a vibrator, one state of output is stable while the other is quasi-stable (unstable). For auto-triggering of output from quasi-stable state to stable state energy is stored by an externally connected capacitor C to a reference level. The time taken in storage determines the pulse width. The transition of output from stable state to quasi-stable state is accomplished by external triggering. The schematic of a 555 timer in monostable mode of operation is shown in figure 2.6.[1][3]

Fig2.6 555-Timer-Monostable-Multivibrator

2.15.1 MONOSTABLE MULTIVIBRATOR CIRCUIT DETAILSPin 1 is grounded. Trigger input is applied to pin 2. In quiescent

condition of output this input is kept at + VCC. To obtain transition of output from stable state to quasi-stable state, a negative-going pulse of narrow width (a width smaller than expected pulse width of output waveform)  and amplitude of greater than + 2/3 VCC is applied to pin 2. Output is taken from pin 3. Pin 4 is usually connected to + VCC to avoid accidental reset. Pin 5 is grounded through a 0.01 u F capacitor to avoid noise problem. Pin 6 (threshold) is shorted to pin 7. A resistor RA is connected between pins 6 and 8. At pins 7 a discharge capacitor is connected while pin 8 is connected to supply VCC.2.15.2 555 IC MONOSTABLE MULTIVIBRATOR OPERATIONS

Fig2.7 555 Monostable-Multivibrator-Operation

For explaining the operation of timer 555 as a monostable multivibrator, necessary internal circuitry with external connections are shown in figureThe operation of the circuit is explained below:

Initially, when the output at pin 3 is low i.e. the circuit is in a stable state, the transistor is on and capacitor- C is shorted to ground. When a negative pulse is applied to pin 2, the trigger input falls below +1/3 VCC, the output of comparator goes high which resets the flip-flop and consequently the transistor turns off and the output at pin 3 goes high. This is the transition of the output from stable to quasi-stable state, as shown in figure. As the discharge transistor is cutoff, the capacitor C begins charging toward +VCC through resistance RA with a time constant equal to RAC. When the increasing capacitor voltage becomes slightly greater than +2/3 VCC, the output of comparator 1 goes high, which sets the flip-flop. The transistor goes to saturation, thereby discharging the capacitor C and the output of the timer goes low, as illustrated in figure 2.7.

Thus the output returns back to stable state from quasi-stable state.The output of the Monostable Multivibrator remains low until a trigger pulse is again applied. Then the cycle repeats. Trigger input, output voltage and capacitor voltage waveforms are shown in figure.

2.15.3 MONOSTABLE MULTIVIBRATOR DESIGN USING 555 TIMER IC

The capacitor C has to charge through resistance RA. The larger the time constant RAC, the longer it takes for the capacitor voltage to reach +2/3VCC.In other words, the RC time constant controls the width of the output pulse. The time during which the timer output remains high is given as:

tp =1.0986RAC, where RA is in ohms and C is in farads.

The pulse width of the circuit may range from micro-seconds to many seconds. This circuit is widely used in industry for many different timing applications.

2.16 GENERAL FUNCTIONAL DESCRIPTIONOn power up, pin 23 is pulled low through resistor R7 to enable the

device for operation. Toggling this pin by switch S9 also resets several message management features. Pin no 27 is pulled low to enable recording and

it is pulled high for playback. To start recording playback switch the appropriate trigger pin as described in the circuit. Glowing of the LED indicates that the device is busy and no commands can be currently accepted. The LED is driven by PNP transistor T1 which is connected to pin 10 of the chip. LED2 indicates recording in each individual memory segment. It is driven by pin 22 through transistor.

2.17 FULL CIRCUIT STRUCTURE & EXPLANATIONBelow the Fig 2.8 shows the final implemented electro circuit of

Gas & Heat Sensor along with auto dial up logic and voice recording and playback device APR. The complete explained description of circuit is as follows:

Firstly we ON the Power supply of 230V AC to provide to the circuit. The AC is then step down by transformer to 12V, which is then used for circuit. The 12V AC is rectified using bridge rectifier to 9V DC supply. Now as per the requirement we certainly use 9V and 5V DC supply. To remove out the ripples came during rectification we applied filter circuit which block ripples to move in forward direction. For 9V supply we use direct after filter circuit & for the 5V we add the IC 7805 as voltage regulator. After IC 7805 we again filter ripples present if any. Now the power circuitry is completed.

Before starting from any one test we will reset the whole circuit last configuration for better results. Let us take Gas Sensor firstly, if we place sensor in the place of leakage the inner circuit of MQ-6 sensor will short circuit by the concentration level above than 8 ppm, which as the result give trigger input to IC 555. Trigger input is applied to pin 2. In quiescent condition of output this input is kept at + VCC. To obtain transition of output from stable state to quasi-stable state, a negative-going pulse of narrow width (a width smaller than expected pulse width of output waveform)  and  amplitude of greater than + 2/3 VCC is applied to pin 2. Output is taken from pin 3, which is applied to Microcontroller 8951 IC. At the same time a exhaust fan is given ON signal by IC 555 for Gas Sensor & fan starts exhausting gas from ambient place. Microcontroller port 3.3 is for Gas Sensor output. As 8951 is coded for it, it then sends signal to the relay circuitry & APR for play recording message. Relay that already connected to hands free will redial the last call or concerned authorities of home, industry, hotel etc. APR will play pre recorded message so the information is sent to owner & if within time limit someone approaches there, chances of accident can be easily eliminated.

Along with dial up logic & message management, there’s implementation of Buzzer & LED in the circuit which will ON as there is any type of detection so the person nearby can watch & hear & safe lives by an unexpected mishaps.

Talking about Heat Sensor now, in case of short circuits at homes, industries etc there arise high flames of fire and also there is some places where excess of heat is too dangerous. Heat sensor element senses it n give signal to triggered input IC 555. The IC 555 output is now connected to port 3.2 of IC 8951. The main difference here is that the exhaust fan will not work during heat sensing case. The rest working of Microcontroller will be the same. As Microcontroller 8951 is coded for it, it then sends signal to the relay circuitry & APR for play recording message. Relay that already connected to hands free will redial the last call or concerned authorities of home, industry, hotel etc. APR will play pre recorded message so the information is sent to owner & if within time limit someone approaches there, chances of accident can be easily eliminated.

This is all about how stuff works. !!

CHAPTER – 3 MICROCONTROLLER AT89C51

3.1 AT89C51 MICROCONTROLLER3.1.1 FEATURES

Compatible with MCS-51™ Products 4K Bytes of In-System Reprogrammable Flash Memory Endurance: 1,000 Write/Erase Cycles RAM is 128 bytes. 2.7V to 6V Operating Range. Fully Static Operation: 0 Hz to 24 MHz 128*8-bit Internal RAM. 32 Programmable I/O Lines. Two 16-bit Timer/Counters. Six Interrupt Sources. Programmable Serial UART Channel. Low power Idle and Power-down Modes Three Level Program Memory Lock

3.1.2 DESCRIPTIONThe AT89C51 is a low-power, high-performance CMOS 8-bit

microcomputer with 4K bytes of Flash Programmable and Erasable Read Only Memory (PROM). The device is manufactured using Atmel’s high density nonvolatile memory technology and is compatible with the industry standard MCS-51™ instruction set and pin out. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the ATMEL AT89C51 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications. The AT89C51 provides the following standard features: 4K bytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, five vector two-level interrupt architecture, a full duplex serial port, and on-chip oscillator and clock circuitry.

In addition, the AT89C51 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The idle mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The Power down

Mode saves the RAM contents but freezes the oscillator disabling all other chip functions until the next hardware reset.

3.2 ARCHITECTURE OF 8951 FAMILYFigure 3.1 shows the architecture of AT89C51 Microcontroller

Fig 3.1 Basic Architecture of AT89C51 Microcontroller

3.2.1 PIN DESCRIPTIONAT89C51 is an 8-bit microcontroller and belongs to Atmel's 8051

family. ATMEL 89C51 has 4KB of Flash programmable and erasable read only memory (PEROM) and 128 bytes of RAM. It can be erased and program to a maximum of 1000 times.  In 40 pin AT89C51, there are four ports designated as P1, P2, P3 and P0. All these ports are 8-bit bi-directional ports, i.e., they can be used as both input and output ports. Except P0 which needs external pull-ups, rest of the ports have internal pull-ups. When 1s are written to these port pins, they are pulled high by the internal pull-ups and can be used as inputs. These ports are also bit addressable and so their bits can also be accessed individually. 

Port P0 and P2 are also used to provide low byte and high byte addresses, respectively, when connected to an external memory. Port 3 has multiplexed pins for special functions like serial communication, hardware interrupts, timer inputs and read/write operation from external memory. AT89C51 has an inbuilt UART for serial communication. It can be programmed to operate at different baud rates. Including two timers & hardware interrupts, it has a total of six interrupts.

Fig 3.2 Pin Diagram of Micro controller 8951

3.2.1 VCCPin 40 provides supply voltage to the chip. The voltage source is +5V.

3.2.2 GNDPin 20 of 8951 is connected to ground.

3.2.3 PORT 0Port 0 is an 8-bit open drain bidirectional I/O port. As an output port

each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high impedance inputs. Port 0 may also be configured to be the

multiplexed low order address/data bus during accesses to external program and data memory. In this mode P0 has internal pull-ups. Port 0 also receives the code bytes during Flash programming, and outputs the code bytes during program verification.

External pull-ups are required during program verification.

3.2.4 PORT 1Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 1

output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. Port 1 also receives the low-order address bytes during flash programming and verification.

3.2.5 PORT 2Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 2

output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that uses 16-bit addresses (MOVX @ DPTR). In this application it uses strong internal pull-ups when emitting 1s. During accesses to external data memory that uses 8-bit addresses (MOVX @ RI); Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the high order address bits and some control signals during Flash programming and verification.

 Pin No

  Function  Name

1

8 bit input/output port (P1) pins

P1.0

2 P1.1

3 P1.2

4 P1.3

5 P1.4

6 P1.5

7 P1.6

8 P1.7

9 Reset pin; Active high Reset

10Input (receiver) for serial communication

Rx D

8 bit input/output port (P3) pins

P3.0

11Output (transmitter) for serial communication

Tx D P3.1

12 External interrupt 1 Int0 P3.2

13 External interrupt 2 Int1 P3.3

14 Timer1 external input T0 P3.4

15 Timer2 external input T1 P3.5

16Write to external data memory.

Write P3.6

17Read from external data memory.

Read P3.7

18Quartz crystal oscillator (up to 24 MHz).

Crystal 2

19 Crystal 1

20 Ground (0V). Ground

21

8 bit input/output port (P2) pinsHigh-order address bits when interfacing with external memory. 

 P2.0/ A8

22  P2.1/ A9

23  P2.2/ A10

24  P2.3/ A11

25  P2.4/ A12

26  P2.5/ A13

27  P2.6/ A14

28  P2.7/ A15

29Program store enable; Read from external program memory.

PSEN

30Address Latch Enable ALE

Program pulse input during Flash programming Prog

31

External Access Enable;  VCC for internal program executions

EA

Programming enable voltage; 12V (during Flash programming)

VPP

32 8 bit input/output port (P0) pins. Low-order address bits when interfacing with external

 P0.7/ AD7

33  P0.6/ AD6

34  P0.5/ AD5

memory. 

35  P0.4/ AD4

36  P0.3/ AD3

37  P0.2/ AD2

38  P0.1/ AD1

39  P0.0/ AD0

40 Supply Voltage; 5V (up to 6.6V) Vcc

Table 3.1 Pin Diagram of AT89C51

3.2.6 PORT 3Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 3

output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (I IL) because of the pull-ups. Port 3 also serves the functions of various special features of the AT89C51 as listed below:

Port 3 also receives some control signals for Flash programming and verification.

3.2.7 RSTReset input. A high on this pin for two machine cycles while the

oscillator is running resets the device.

3.2.8 PORT PIN ALTERNATE FUNCTIONSThe alternate functions of port 3 of 8951 are as follows in table 3.2

Port Pin Alternate Functions

P3.0 RXD (serial input port)

P3.1 TXD (serial output port)

P3.2 INT 0 (external interrupt 0)

P3.3 INT 1 (external interrupt 1)

P3.4 T0 (timer 0 external input)

P3.5 T1 (timer 1 external input)

P3.6 WR (external data memory write strobe)

P3.7 RD (external data memory read strobe)

Table 3.2 Port 3 Functions

3.2.9 ALE/PROGAddress Latch Enable output pulse for latching the low byte of the

address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming. In normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency, and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external Data Memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode.

3.2.10 PSEN

Program Store Enable is the read strobe to external program memory.This is an output pin. PSEN stands for “program store enable.” In an 8031-based system in which an external ROM holds the program code, this pin is connected to the OE pin of the ROM

When the AT89C51 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory.

3.2.11 EA/VPPExternal Access Enable. EA must be strapped to GND in order to enable

the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to VCC for internal program executions. This pin also receives the 12-volt programming enable voltage (VPP) during Flash programming, for parts that require 12-volt VPP.

3.2.12 XTAL 1Input to the inverting oscillator amplifier and input to the internal clock

operating circuit.

3.2.13 XTAL 2Output from the inverting oscillator amplifier.

3.2.14 OSCILLATOR CHARACTERISTICSXTAL 1 and XTAL 2 are the input and output, respectively, of an inverting

amplifier which can be configured for use as an on-chip oscillator, as shown in Figure 1. Either a quartz crystal or ceramic resonator may be used. To drive the device from an external clock source, XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure 3.4.There are no requirements on the duty cycle of the external clock signal, since the input to the internal clocking circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high and low time specifications must be observed.3.2.15 IDLE MODE

In idle mode, the CPU puts itself to sleep while all the on chip peripherals remain active. The mode is invoked by software. The content of the on-chip RAM and all the special functions registers remain unchanged during this mode. The idle mode can be terminated by any enabled Interrupt or by hardware reset. It should be noted that when idle is terminated by a hardHardware reset, the device normally resumes program execution, from where it left off, up to two machine cycles before the internal reset algorithm takes control. On-chip hardware inhibits access to internal RAM in this event, but

access to the port pins is not inhibited. To eliminate the possibility of an unexpected write to a port pin when Idle is terminated by reset, the instruction following the one that invokes Idle should not be one that writes to a port pin or to external memory.

Fig 3.3 Oscillator connection3.2.16 STATUS OF EXTERNAL PINS DURING IDLE AND POWER-DOWN MODES

During the 2 modes, idle & power, the status of external pins are described in table 3.3.

ModeProgram Memory ALE PORT0 PORT1 PORT2 PORT3PSEN

Idle Internal 1 1 Data Data Data Data

Idle External 1 1 Float Data Address Data

Power-down Internal 0 0 Data Data Data Data

Power-down External 0 0 Float Data Data Data

Table 3.3 Status of External Pins during Idle and Power-Down Modes

Figure 3.4 External Clock Drive Configuration

3.2.17 POWER DOWN MODEIn the power down mode the oscillator is stopped, and the instruction

that invokes power down is the last instruction executed. The on-chip RAM and Special Function Registers retain their values until the power down mode is terminated. The only exit from power down is a hardware reset. Reset redefines the SFRs but does not change the on-chip RAM. The reset should not be activated before VCC is restored to its normal operating level and must be held active long enough to allow the oscillator to restart and stabilize.

3.2.18 PROGRAMMING THE FLASHThe AT89C51 is normally shipped with the on-chip Flash memory array

in the erased state (that is, contents = FFH) and ready to be programmed. The programming interface accepts either a high-voltage (12-volt) or a low-voltage (VCC) program enable signal. The low-voltage programming mode provides a convenient way to program the AT89C51 inside the user’s system, while the high-voltage programming mode is compatible with conventional third-party Flash or EPROM programmers.

The AT89C51 is shipped with either the high-voltage or low-voltage programming mode enabled. The respective top-side marking and device signature codes are listed in the following table 3.4.

The AT89C51 code memory array is programmed byte-by-byte in either programming mode. To program any non-blank byte in the on-chip Flash Memory, the entire memory must be erased using the Chip Erase Mode.

Table 3.4 Flash Programming Mode Signature Codes

3.2.19 PROGRAM MEMORY LOCK BITSOn the chip are three lock bits which can be left un-programmed (U) or

can be programmed (P) to obtain the

additional features listed in the table below:

When lock bit 1 is

programmed, the logic level at the EA pin is sampled and latched during reset. If the device is powered up without a reset, the latch initializes to a random value, and holds that value until reset is activated. It is necessary that the latched value of EA be in agreement with the current logic level at that pin in order for the device to function properly.

VPP = 12V VPP = 5V

Top-side Mark AT89C51 AT89C51

xxxx xxxx-5Yyww yyww

Signature (030H) = 1EH (030) = 1EH(031H) = 51H (031) = 51H(032H) =F FH (032) = 05H

3.2.20 LOCK BIT PROTECTION MODES

Program Lock Bits

MODE LB1 LB2 LB3 Protection Type

1 U U U No program lock features

2 P U U

MOVC instructions executed from external program memory are disabled fromfetching code bytes from internal memory, EA is sampled and latched on reset,and further programming of the Flash is disabled

3 P P U Same as mode 2, also verify is disabled

4 P P PSame as mode 3, also external execution is disabled

Table 3.5 Lock Bit Protection Modes

The above figure 3.5 signifies the lock bit protection modes of 8951.

3.3 PROGRAMMING ALGORITHMBefore programming the AT89C51, the address, data and control signals

should be set up according to the Flash programming mode table and Figures. To program the AT89C51, take the following steps.

Input the desired memory location on the address lines.

Input the appropriate data byte on the data lines.

Activate the correct combination of control signals.

Raise EA/VPP to 12V for the high-voltage programming mode.

Pulse ALE/PROG once to program a byte in the Flash array or the lock bits

The byte-write cycle is self-timed and typically takes no more than 1.5 ms. Repeat steps 1 through 5, changing the address and data for the entire array or until the end of the object file is reached.

3.3.1 DATA POLLINGThe AT89C51 features Data Polling to indicate the end of a write cycle.

During a write cycle, an attempted read of the last byte written will result in the complement of the written datum on PO.7. Once the write cycle has been completed, true data are valid on all outputs, and the next cycle may begin. Data Polling may begin any time after a write cycle has been initiated.

3.3.2 READY/BUSY The progress of byte programming can also be monitored by the RDY/BSY output signal. P3.4 is pulled low after ALE goes high during programming to indicate BUSY. P3.4 is pulled high again when programming is done to indicate READY.

3.3.3 PROGRAM VERIFY If lock bits LB1 and LB2 have not been programmed, the programmed

code data can be read back via the address and data lines for verification. The lock bits cannot be verified directly. Verification of the lock bits is achieved by observing that their features are enabled.

3.3.4 CHIP ERASE

The entire Flash array is erased electrically by using the proper combination of control signals and by holding ALE/PROG low for 10 ms. The code array is written with all “1”s. The chip erase operation must be executed before the code memory can be re-programmed.

3.3.5 READING THE SIGNATURE BYTESThe signature bytes are read by the same procedure as a normal

verification of locations 030H, 031H, and 032H, except that P3.6 and P3.7 must be pulled to a logic low. The values returned are as following table 3.6.

(030H) = 1EH indicates manufactured by Atmel

(031H) = 51H indicates 89C51

(032H) = FFH indicates 12V programming

(032H) = 05H indicates 5V programming

Table 3.6 Signature Bytes

3.4 PROGRAMMING INTERFACEEvery code byte in the Flash array can be written and the entire array

can be erased by using the appropriate combination of control signals. The write operation cycle is self timed and once initiated, will automatically time itself to completion. All major programming vendors offer worldwide support for the Atmel microcontroller series.

3.5 SPECIAL FUNCTION REGISTER (SFR) ADDRESSESFigure 3.7 shows the addresses of Special Function Register.

ACC ACCUMULATOR 0E0H

B B REGISTER 0F0H

PSW PROGRAM STATUS WORD 0D0H

SP STACK POINTER 81H

DPTR DATA POINTER 2 BYTES

DPL LOW BYTE OF DPTR 82H

DPH HIGH BYTE OF DPTR 83H

P0 PORT0 80H

P1 PORT1 90H

P2 PORT2 0A0H

P3 PORT3 0B0H

TMOD TIMER/COUNTER MODE CONTROL

89H

TCON TIMER COUNTER CONTROL

88H

TH0 TIMER 0 HIGH BYTE 8CH

TLO TIMER 0 LOW BYTE 8AH

TH1 TIMER 1 HIGH BYTE 8DH

TL1 TIMER 1 LOW BYTE 8BH

SCON SERIAL CONTROL 98H

SBUF SERIAL DATA BUFFER 99H

PCON POWER CONTROL

Table 3.7 SFR Addresses

3.5.1 TMOD (TIMER MODE) REGISTER

Fig 3.5 TMOD RegisterBoth timers are the 89c51 share the one register TMOD. 4 LSB bit for

the timer 0 and 4 MSB for the timer 1. In each case lower 2 bits set the mode of the timer, Upper two bits set the operations.

3.5.1.1 GATE

Gating control when set. Timer/counter is enabled only while the INTX pin is high and the TRx control pin is set. When cleared, the timer is enabled whenever the TRx control bit is set

3.5.1.2 C/TTimer or counter selected cleared for timer operation (input from

internal system clock)

M1 M0 MODE OPERATING MODE

0 0 0 13 BIT TIMER/MODE

0 1 1 16 BIT TIMER MODE

1 0 2 8 BIT AUTO RELOAD

1 1 3 SPLIT TIMER MODE

Table 3.8 Modes of Operation

M1 Mode bit 1

M0 Mode bit 0

3.5.2 PSW (PROGRAM STATUS WORD)Below are the contents of PSW in figure 3.6 & details in table 3.9

Fig 3.6 PSW Register

CY PSW.7 CARRY FLAG

AC PSW.6 AUXILIARY CARRY

F0 PSW.5 AVAILABLE FOR THE USER FRO GENERAL PURPOSE

RS1 PSW.4 REGISTER BANK SELECTOR BIT 1

RS0 PSW.3 REGISTER BANK SELECTOR BIT 0

0V PSW.2 OVERFLOW FLAG

-- PSW.1 USER DEFINABLE BIT

P PSW.0 PARITY FLAG SET/CLEARED BY HARDWARE

Table 3.9 PSW Register Details

3.5.3 PCON – POWER CONTROL REGISTERAddress: 87H (not bit addressable)

SMOD – Serial mode bit used to determine the baud rate with Timer 1.

Baud Rate

If SMOD = 0 then N = 384. If SMOD = 1 then N = 192. TH1 is the high byte of timer 1 when it is in 8-bit auto reload mode.

GF1 and GF0 are General purpose flags not implemented on the standard device PD is the power down bit. Not implemented on the standard device IDL activate the idle mode to save power. Not implemented on the standard device.

D7 D6 D5 D4 D3 D2 D1 D0SMOD X x x GF1 GF0 PD IDL

Table 3.10 PCON Register

There are two ways to increase the baud rate of data transfer in the 8051 To use a higher frequency crystal To change a bit in the PCON registerPCON register is an 8 bit register. Of the 8 bits, some are unused, and some

are used for the power control capability of the 8051. The bit which is used for the serial communication is D7, the SMOD bit. When the 8051 is powered up, D7 (SMOD BIT) OF PCON register is zero. We can set it to high by software and thereby double the baud rate. Table 3.11 shows the Baud Rate comparison for XTAL

TH1 (DECIMAL)

HEX SMOD =0

SMOD =1

-3 FD 9600 19200

-6 FA 4800 9600

-12 F4 2400 4800

-24 E8 1200 2400

Table 3.11 Baud Rate Comparison for XTAL = 11.0592 MHZ

3.5.4 TCON – TIMER CONTROL REGISTERTable 3.12 shows the TCON register.

D7 D6 D5 D4 D3 D2 D1 D0TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0

Table 3.12 TCON Register

Address: 88H (bit addressable)

TF1 – Timer 1 overflow flagTR1 – Timer 1 run control bitTF0 – Timer 0 overflow flagTR0 – Timer 0 run control bitIE1 – External interrupt 1 edge flag. Set to 1 when edge detected.IT1 – Edge control bit for external interrupt 1. 1 = edge, 0 = levelIE0 – External interrupt 0 edge flag. Set to 1 when edge detectedIT0 – Edge control bit for external interrupt 0. 1 = edge, 0 = level

3.5.5 SCON – SERIAL CONTROL REGISTERTable 3.13 shows the SCON register.

D7 D6 D5 D4 D3 D2 D1 D0SM0 SM1 SM2 REN TB8 RB8 TI RI

Table 3.13 SCON Register

SM2 – Enables multiprocessor communication in modes 2 and 3. REN – Receiver enable TB8 – Transmit bit 8. This is the 9th bit transmitted in modes 2 and 3. RB8 – Receive bit 8. This is the 9th bit received in modes 2 and 3. TI – Transmit interrupt flag. Set at end of character transmission. Cleared in software. RI – Receive interrupt flag. Set at end of character reception. Cleared in software.

SM0 SM1 Operation

Baud rate

0 0 Shift Osc/12

register

0 1 8-bit UART

Set by timer

1 0 9-bit UART

Osc/12 or Osc/64

1 1 9-bit UART

Set by timer

Table 3.14 Modes of SCON Register

3.5.6 TMOD – TIMER MODE CONTROL REGISTERD7 D6 D5 D4 D3 D2 D1 D0

Gate C/T M1 M0 Gate C/T M1 M0

Timer 1 Timer 0

Table 3.15 TMOD Register

M1 M0 Mode

0 0 13-bit mode for compatibility to 8048 family

0 1 16- bit Timer/Counter. User must reload in software

1 0 8-bit autoreload. TLx is automatically reloaded from THx

1 1 TL0 is 8-bit counter controlled by Timer0 control bits. TH0 is 8-bit counter controlled by Timer1 control bits. Timer 1 is stopped

Table 3.16 Modes of TMOD

3.5.7 IE – INTERRUPT ENABLE REGISTERTable 3.17 represents the IE register.

D7 D6 D5 D4 D3 D2 D1 D0EA X ET2 ES ET1 EX1 ET0 EX0

Table 3.17 IE Register

Address: 0A8H (bit addressable) EA – Global interrupt enable x – Not defined ET2 – Timer 2 interrupt enable ES – Serial port interrupt enable ET1 – Timer 1 interrupt enable EX1 – External interrupt 1 enable ET0 – Timer 0 interrupt enable EX0 – External interrupt 0 enable

3.5.8 IP – INTERRUPT PRIORITY REGISTERTable 3.18 represents the IP register.

D7 D6 D5 D4 D3 D2 D1 D0x x PT2 PS PT1 PX1 PT0 PX0

Table 3.18 IP Register

Address: 0B8H (bit addressable) x – Not defined PT2 – Priority for timer 2 interrupt PS – Priority for serial port interrupt PT1 – Priority for timer 1 interrupt PX1 – Priority for external interrupt 1 PT0 – Priority for timer 0 interrupt PX0 – Priority for external interrupt 0

3.5.9 T2CON – TIMER 2 CONTROL REGISTERAddress: 0C8H (bit addressable) TF2 – Timer 2 overflow flag EXF2 – Timer 2 external flag.

D7 D6 D5 D4 D3 D2 D1 D0

TF2 EXF2 RCLK TCLK EXEN2 TR2 C/T2 CP/ RL2

Table 3.19 T2CON Register

RCLK – Receive clock. When set causes the serial port to use timer 2 for reception. TCLK – Transmit clock. When set causes the serial port to use timer 2 for transmission.C/ T2 - Counter/Timer select.if 0 use internal timer if 1 use external pin CP/ RL2 - Capture/reload flag.

3.6 MCS-51 FAMILY INSTRUCTION SETThe instruction set is divided in to 5 categories. They are as follows:1. Arithmetic instructions

2. Logic instructions.

3. Data transfer instructions.

4. Boolean variable manipulation instruction.

5. Program and machine control instruction.

We have listed all the instructions of microcontroller with description, Bytes, & Cycles, which is figured out and described by next page.

Fig 3.8 Arithmetic Operation

Fig 3.9 Logic Operation

3.10 Data Transfer Operation

Fig 3.11 Boolean Manipulation & Program & Machine Control Operation

Instructions are explained in alphabetical order.3.6.1 ACALL TARGET ADDRESSFunction: Absolute callFlags: NoneDescription: ACALL unconditionally calls a subroutine located at the indicated address. The instruction increments the PC twice to obtain the address of the following instruction, then pushes the 16-bit result onto the stack (low-order byte first) and increments the stack pointer twice. The destination address is obtained by successively concatenating the five high-order bits of the incremented PC, op code bits 7-5, and the second byte of the instruction.

The subroutine called must therefore start within the same 2K block of program memory as the first byte of the instruction following ACALL. No flags are affected.Example: Initially SP equals 07H. The label “SUBRTN” is at program memory location 0345H. After executing the instruction ACALL SUBRTN at location 0123H, SP will contain 09H, internal RAM location 08H and 09H will contain 25H and 01H, respectively, and the PC will contain 0345H.Operation: ACALL(PC) ← (PC) + 2(SP) ← (SP) + 1((SP)) ← (PC7-0)(SP) ← (SP) + 1((SP)) ←(PC15-8)(PC10-0) ← page addressBytes: 2Cycles: 23.6.2 ADD A, SOURCEBYTEFunction: AddFlags: OV, AC, CYDescription: ADD adds the byte variable indicated to the accumulator, leaving the result in the accumulator. The carry and auxiliary carry flags are set, respectively, if there is a carry out of bit 7 or bit 3, and cleared otherwise. When adding unsigned integers, the carry flag indicates an overflow occurred. OV is set if there is a carry out of bit 6 but not out of bit 7, or a carry out of bit 7 but not out of bit 6; otherwise OV is cleared. When adding signed integers, OV indicates a negative number produced as the sum of two positive operands, or a positive sum from two negative operands. Four source operand addressing modes are allowed: register, direct, register indirect, or immediate.Example:   

MOV A,#45H ; A = 45HADD A,#4FHResult:  A = 94H, CY = 0.The following addressing modes are supported for the ADD instruction.1. Immediate:  ADD A, #dataExample: ADD A,#40H2. Register:  ADD A, RnExample: ADD A,R13. Direct: ADD A, directExample: ADD A, 20H  ;Add data in RAM location 20H to A4. Register-indirect:    ADD A,@RiExample: ADD A,@R0 ;Add to A data pointed by R0

3.6.3 ADDC A,SOURCEBYTEFunction: Add with carryFlags: OV, AC, CYDescription: ADDC simultaneously adds the byte variable indicated, the carry flag and the accumulator contents, leaving the result in the accumulator. The carry and auxiliary carry flags are set, respectively, if there is a carry out of bit 7 or bit 3, and cleared otherwise. When adding unsigned integers, the carry flag indicates an overflow occurred.OV is set if there is a carry out of bit 6 but not out of bit 7, or a carry out of bit 7 but not out of bit 6; otherwise OV is cleared. When adding signed integers, OV indicates a negative number produced as the sum of two positive operands or a positive sum from two negative operands.Four source operand addressing modes are allowed: register, direct, register indirect, or immediate.Example:       mov a, #0C3H  ; (A) ← 0C3Hmov R0,#0AAH ; (R0) ← 0AAH  assume (CY) = 1ADDC A,R0Result : (A) = 6EH with (AC) = 0, (CY) = 1, (OV) = 1.The addressing modes for ADDC are same as for ADD A,byte.

3.6.4 AJMP TARGET ADDRESSFunction: Absolute jumpFlags: NoneDescription: AJMP transfers program execution to the indicated address, which is formed at runtime by concatenating the high-order five bits of the PC (after incrementing the PC twice), op code bits 7-5, and the second byte of the

instruction. The destination must therefore be within the same 2K block of program memory as the first byte of the instruction following AJMP.Example: The label”JMPADR” is at program memory location 0123H. The instruction AJMP JMPADR is at location 0345H and will load the PC with 0123H.

3.6.5 ANL DEST-BYTE, SRC-BYTEFunction: Logical AND for byte variablesFlags: NoneDescription: ANL performs the bitwise logical AND operation between the variables indicated and stores the results in the destination variable. No flags are affected. The two operands allow six addressing mode combinations. When the destination is a accumulator, the source can use register, direct, register-indirect, or immediate addressing; when the destination is a direct address, the source can be the accumulator or immediate data.Note: When this instruction is used to modify an output port, the value used as the original port data will be read from the output data latch, not the input pins.Example: If the accumulator holds 0C3H (11000011B) and register 0 holds 0AAH (10101010B) then the instruction ANL A,R0 will leave 81H (10000001B) in the accumulator.For an ANL instruction there are a total of six addressing modes.1. Immediate:  ANL A, #dataExample: ANL A,#30H2. Register: ANL A, RnExample: ANL A, R53. Direct: ANL A,directExample: ANL A,20H ; AND A with data in RAM location 20H4. Register-indirect: ANL A, @RiExample: ANL A,@R1; AND A with data pointed by R0In the next two addressing modes the destination is direct address while the source is either A or immediate data.5. ANL direct,AExample: ANL 20H, A6. ANL direct, #dataExample: ANL 40H, #30H

3.6.6 ANL C, SRC-BITFunction: Logical AND for bit variablesFlags: CY

Description: In this instruction the carry flag bit is ANDed with a source bit and the result is placed in carry. If the Boolean value of the source bit is a logic 0 then clear the carry flag; otherwise leave the carry flag in its current state. Only direct bit addressing is allowed for the source operand. A slash (”/”) preceding the operand in the assembly language indicates that the logical complement of the addressed bit is used as the source value, but the source bit itself is not affected.

3.6.7 CJNE DEST-BYTE, SRC-BYTE, TARGETFunction: Compare and jump if not equalFlags: CYDescription: CJNE compares the magnitudes of the first two operands, and branches if their values are not equal. The branch destination is computed by adding the signed relative displacement in the last instruction byte to the PC, after incrementing the PC to the start of the next instruction. The carry flag is set if the unsigned integer value of dest-byte is less than the unsigned integer value of src-byte; otherwise, the carry is cleared. Neither operand is affected.The first two operands allow four addressing mode combinations: the accumulator may be compared with any directly addressed byte or immediate data, and any indirect RAM location or working register can be compared with an immediate constant.Example:1. Immediate: CJNE A, #data, targetExample: CJNE A, #40,GO ; JUMP if A is not 402. Direct: CJNE A, direct, targetExample: CJNE A, 20H,GO ; JUMP if A !=(20H)3. Register:  CJNE Rn,#data,targetExample: CJNE R5,#70,GO ; jump if R5 is not 70In the fourth addressing mode, any RAM location can be destination. The RAM location is held by register R0 or R1.4. Register-indirect: CJNE @Ri,#data,targetExample: CJNE @R1,#40,GO ;Jump if RAM location whose address is held by R1 is not equal to 40.

3.6.8 CLR AFunction: Clear accumulatorFlags: None are affectedDescription: The accumulator is cleared (all bits set to zero).Example: The accumulator contains 5CH. The instruction CLR A will leave the accumulator set to 00H.

3.6.9 CLR BITFunction: Clear bitFlags: None are affectedDescription: The indicated bit is cleared (reset to zero).  CLR can operate on the carry flag or any directly addressable bit.Example: Port 1 has previously been written with 5DH (01011101B). The instruction CLR P1.2 will leave the port set to 59H (01011001B).

3.6.10 CPL AFunction: Complement accumulatorFlags: None are affectedDescription: Each bit of the accumulator is logically complemented (one’s complement). Bits which previously contained a one are changed to zero and vice versa.Example: The accumulator contains 5CH (01011100B). The instruction CPL A will leave the accumulator set to 0A3H (10100011 B).

3.6.11 CPL BITFunction: Complement bitFlags: None are affectedDescription: The bit variable specified is complemented. A bit which had been a one is changed to zero and vice versa. CPL can operate on the carry or any directly addressable bit.Example: Port 1 has previously been written with 5DH (01011101B).The instruction sequenceCPL P1.1CPL P1.2 Will leave the port set to 5BH (01011011B).

3.6.12 DA AFunction: Decimal adjust accumulator after additionFlags: CYDescription: DA A adjusts the eight-bit value in the accumulator resulting from the earlier addition of two variables (each in packed BCD format), producing two four-bit digits. Any ADD or ADDC instruction may have been used to perform the addition. If accumulator bits 3-0 are greater than nine (1010-1111), or if the AC flag is one, six is added to the accumulator

producing the proper BCD digit in the low order nibble. This internal addition would set the carry flag if a carry-out of the low order four-bit field propagated through all high-order bits, but it would not clear the carry flag otherwise. If the carry flag is now set, or if the four high-order bits now exceed nine (1010-1111), these high-order bits are incremented by six, producing the proper BCD digit in the high-order nibble. Again, this would set the carry flag if there was a carryout of the high-order bits, but wouldn’t clear the carry. The carry flag thus indicates if the sum of the original two BCD variables is greater than 100, allowing multiple precision decimal additions. OV is not affected. All of this occurs during the one instruction cycle. Essentially; this instruction performs the decimal conversion by adding 00H, 06H, 60H, or 66H to the accumulator, depending on initial accumulator and PSW conditions.Note:  DA A cannot simply convert a hexadecimal number in the accumulator to BCD notation, nor does DA A apply to decimal subtraction.Example:    MOV A, #47HADD A, #38HDA AResult:        47H+ 38H———–7FH          (invalid BCD)06H          (after DA A)———–85H          (valid BCD)———–In the above instruction, since the lower nibble was greater than 9, DA added 6 to A. If the lower nibble is less than 9 but AC=1, it also adds 6 to the lower nibble.

3.6.13 DEC BYTEFunction: DecrementFlags: NoneDescription: The variable indicated is decremented by 1. An original value of 00H will underflow to 0FFH. Four operand addressing modes are allowed:1. Accumulator: DEC A2. Register:  DEC Rn3. Direct:   DEC direct4. Register-indirect: DEC @Ri

3.6.14 DIV ABFunction: DivideFlags: CY and OVDescription: DIV AB divides the unsigned eight-bit integer in the accumulator by the unsigned eight-bit integer in register B. The accumulator receives the integer part of the quotient; register B receives the integer remainder. The carry and OV flags will be cleared.Exception: If B had originally contained 00H, the values returned in the accumulator and B register will be undefined and the overflow flag will be set. The carry flag is cleared in any case.Example:MOV A,#35MOV B,#10DIV ABResult:  A=3 and B=5

3.6.15 DJNZ BYTE,TARGETFunction: Decrement and jump if not zeroFlags: NoneDescription: DJNZ decrements the location indicated by 1, and branches to the address indicated by the second operand if the resulting value is not zero. An original value of 00H wills underflow to 0FFH. The branch destination would be computed by adding the signed relative-displacement value in the last instruction byte to the PC, after incrementing the PC to the first byte of the following instruction.The following two formats are supported by this instruction.1. Register: DJNZ Rn, targetExample: DJNZ R3, HERE2. Direct: DJNZ direct, target

3.6.16 INC BYTEFunction: IncrementFlags: NoneDescription: INC increments the indicated variable by 1. An original value of 0FFH will overflow to 00H.Four operand addressing modes are allowed:1. Accumulator: INC A2. Register: INC Rn3. Direct: INC direct4. Register-indirect:   INC @Ri

Note: When this instruction is used to modify an output port, the value used as the original port data will be read from the output data latch, not the input pins.

3.6.17 INC DPTRFunction: Increment data pointerFlags: NoneDescription: Increment the 16-bit data pointer by 1. A 16-bit increment (modulo 216) is performed; an overflow of the low-order byte of the data pointer (DPL) from 0FFH to 00H will increment the high- order byte (DPH). This is the only 16-bit register which can be incremented.Example: MOV DPTR, #16FFH       DPTR=16FFHINC DPTRResult: DPTR=1700H

3.6.18 JB BIT,TARGETFunction: Jump if bit is setFlags: NoneDescription: If the indicated bit is a one, jump to the target address indicated; otherwise proceed with the next instruction. The branch destination is computed by adding the signed relative-displacement in the third instruction byte to the PC, after incrementing the PC to the first byte of the next instruction. The bit tested is not modified.Example: SETB P1.2; Make P1.2 an input portHERE: JB P1.2,HERE ; stay here as long as P1.2=1MOV P2,#20H ; Since P1.2=0 send 55H to P2

3.6.19 JBC BIT,TARGETFunction: Jump if bit is set and clear bit.Flags: NoneDescription: If the indicated bit is one, branch to the target address while at the same time clear the designated bit. The branch destination is computed by adding the signed relative displacement in the third instruction byte to the PC, after incrementing the PC to the first byte of the next instruction.Note: When this instruction is used to test an output pin, the value used as the original data will be read from the output data latch, not the input pin.

3.6.20 JC TARGETFunction: Jump if carry is set

Flags: NoneDescription: If the carry flag is set, branch to the target address indicated; otherwise proceed with the next instruction.

3.6.21 JMP @A + DPTRFunction: Jump indirectFlags: NoneDescription: The JMP instruction is an unconditional jump to a target address. The target address provided by the total sum of register A and the DPTR register.

3.6.22 JNB BIT,TARGETFunction: Jump if bit is not setFlags: NoneDescription: If the indicated bit is a zero, branch to the target address; otherwise proceed with the next instruction. The branch destination is computed by adding the signed relative-displacement in the third instruction byte to the PC, after incrementing the PC to the first byte of the next instruction. The bit tested is not modified.Example:SETB P1.2; Make P1.2 an input portHERE: JNB P1.2,HERE; stay here as long as P1.2=0MOV P2,#20H; Since P1.2=1 send 55H to P2

3.6.23 JNC TARGETFunction: Jump if carry is not setFlags: NoneDescription: If the carry flag is a zero, branch to the target address; otherwise proceed with the next instruction. The branch destination is computed by adding the signed relative-displacement in the second instruction byte to the PC, after incrementing the PC twice to point to the next instruction. The carry flag is not modified.

3.6.24 JNZ TARGETFunction: Jump if accumulator is not zeroFlags: NoneDescription: If any bit of the accumulator is a one, branch to the indicated address; otherwise proceed with the next instruction. The branch destination is computed by adding the signed relative-displacement in the second instruction

byte to the PC, after incrementing the PC twice. The accumulator is not modified.

3.6.25 JZ TARGETFunction: Jump if accumulator is zeroFlags: NoneDescription: If all bits of the accumulator are zero, branch to the address indicated; otherwise proceed with the next instruction. The branch destination is computed by adding the signed relative-displacement in the second instruction byte to the PC, after incrementing the PC twice. The accumulator is not modified. No flags are affected.

3.6.26 LCALL 16-BIT ADDRFunction: Long callFlags: NoneDescription: LCALL calls a subroutine located at the indicated address. The instruction adds three to the program counter to generate the address of the next instruction and then pushes the 16-bit result onto the stack (low byte first), incrementing the stack pointer by two. The high-order and low-order bytes of the PC are then loaded, respectively, with the second and third bytes of the LCALL instruction. Program execution continues with the instruction at this address. The subroutine may therefore begin anywhere in the full 64 Kbyte program memory address space.Example: Initially the stack pointer equals 07H. The label”SUBRTN” is assigned to program memory location 1234H. After executing the instruction LCALL SUBRTN at location 0123H, the stack pointer will contain 09H, internal RAM locations 08H and 09H will contain 26H and 01H, and the PC will contain 1234H.

3.6.27 LJMP 16-BIT ADDRFunction: Long jumpFlags: NoneDescription: LJMP causes an unconditional branch to the indicated address, by loading the high order and low-order bytes of the PC (respectively) with the second and third instruction bytes. The destination may therefore be anywhere in the full 64K program memory address space.Example: The label”JMPADR” is assigned to the instruction at program memory location 1234H. The instruction LJMP JMPADR at location 0123H will load the program counter with 1234H.

3.6.28 MOV DEST-BYTE, SRC-BYTEFunction: Move byte variableFlags: NoneDescription: The byte variable indicated by the second operand is copied into the location specified by the first operand. The source byte is not affected. No other register or flag is affected.There are fifteen possible combinations for this instruction. They are as follows:Examples:(a) Register A as the destination. This can have the following formats.1. MOV A, #data         Example: MOV A,#10H2. MOV A, Rn             Example: MOV A,R53. MOV A, direct         Example: MOV A,50H4. MOV A, @Ri           Example: MOV A,@R0(b) Register A is the source. This can have the following formats.1. MOV Rn, A2. MOV direct, A3. MOV @Ri, A(c) Rn is the destination1. MOV Rn, #immediate2. MOV Rn, A3. MOV Rn, direct(d) The destination direct address1. MOV direct, #data2. MOV direct, @ri3. MOV direct, A4. MOV direct, Rn(e) Destination is an indirect address held by R0 and R1.1. MOV @Ri, #data2. MOV @Ri, A3. MOV @Ri, direct

3.6.29 MOV DEST-BIT, SRC-BITFunction: Move bit dataFlags: None

Description: The Boolean variable indicated by the second operand is copied into the location specified by the first operand. One of the operands must be the carry flag; the other may be any directly addressable bit. No other register or flag is affected.Example: MOV P1.2,C ;copy carry bit to port bit P1.2

3.6.30 MOV DPTR, #DATA16Function: Load data pointer with a 16-bit constantFlags: NoneDescription: The data pointer is loaded with the 16-bit constant indicated. The 16 bit constant is loaded into the second and third bytes of the instruction. The second byte (DPH) is the high-order byte, while the third byte (DPL) holds the low-order byte. This is the only instruction which moves 16 bits of data at once.Example: MOV DPTR, #434FH ;DPTR=434FH

3.6.31 MOVC A, @A + BASE-REGFunction: Move code byteFlags: NoneDescription: The MOVC instructions load the accumulator with a code byte, or constant from program memory. The address of the byte fetched is the sum of the original unsigned eight-bit accumulator contents and the contents of a sixteen-bit base register, which may be either the data pointer or the PC. In the latter case, the PC is incremented to the address of the following instruction before being added to the accumulator; otherwise the base register is not altered. Sixteen-bit addition is performed so a carry-out from the low-order eight bits may propagate through higher-order bits.Example: MOVC A, @A + DPTR ; mov data at A+DPTR into AMOVC A, @A + PC ; mov data at A+PC into A

3.6.32 MOVX DEST-BYTE, SRC-BYTEFunction: Move externalFlags: NoneDescription: The MOVX instructions transfer data between the accumulator and a byte of external data memory, hence the”X” appended to MOV. This instruction allows us to access externally connected memory. There are two types of instructions, differing in whether they provide an eight bit or sixteen-bit indirect address to the external data RAM as explained bellow.(a) The 16-bit external memory address is held by the DPTR register.

MOVX A,@DPTRThis moves into the accumulator a byte from external memory whose address is pointed by DPTR.MOVX @DPTR, AThis moves the content of accumulator to the external memory location whose address is held  by DPTR.(b) The 8-bit address of external memory is held by R0 or R1MOVX A,@RiThis moves to the accumulator a byte from external memory whose 8-bit address is pointed by R0 or R1.MOVX @Ri,AThis moves a byte from register A to an external memory whose 8-bit address is held by R0 or R1.

3.6.33 MUL ABFunction: MultiplyFlags: OV, CYDescription: MUL AB multiplies the unsigned eight-bit integers in the accumulator and register B. The low-order byte of the sixteen-bit product is left in the accumulator, and the high-order byte in B. If the product is greater than 255 (0FFH) the overflow flag is set; otherwise it is cleared. The carry flag is always cleared.Example:      MOV A,#5MOV B,#7MUL ABResult: A=35=23H, B=0

3.6.34 NOPFunction: No operationFlags: NoneDescription: This performs no operation and execution continues with the next instruction. It is sometimes used for timing delays to waste clock cycles. This instruction only updates the PC to point to the next instruction following NOP.

3.6.35 ORL DEST-BYTE, SRC-BYTEFunction: Logical OR for byte variablesFlags: None

Description: ORL performs the bitwise logical OR operation between the indicated variables, storing the results in the destination byte.The two operands allow six addressing mode combinations. When the destination is the accumulator, the source can use register, direct, register-indirect, or immediate addressing; when the destination is a direct address, the source can be the accumulator or immediate data.Note: When this instruction is used to modify an output port, the value used as the original port data will be read from the output data latch, not the input pins.Example: If the accumulator holds 0C3H (11000011B) and R0 holds 55H (01010101B) then the instruction ORL A,R0 will leave the accumulator holding the value 0D7H (11010111B).Different types of addressing modes are as follows.1. Immediate:  ORL A, #dataExample: ORL A,#30h2. Register:  ORL A, RnExample: ORL A, R53. Direct:  ORL A,directExample: ORL A,20H; OR A with data in RAM location 20H4. Register-indirect: ORL A, @RiExample: ORL A,@R1; OR A with data pointed by R0.

3.6.36 ORL C, SRC-BITFunction: Logical OR for bit variablesFlags: CYDescription: In this instruction the carry flag bit is ANDed with a source bit and the result is placed in carry. If the Boolean value of the source bit is logic 0 then clear the carry flag; otherwise leave the carry flag in its current state. Only direct bit addressing is allowed for the source operand. A slash (”/”) preceding the operand in the assembly language indicates that the logical complement of the addressed bit is used as the source value, but the source bit itself is not affected. No other flags are affected.

3.6.37 POP DIRECTFunction: Pop from stackFlags: NoneDescription: This copies the byte pointed by SP to the location whose direct address indicated, and decrements SP by 1. Notice that this instruction supports only direct addressing mode. Therefore, instruction such as POP A, POP R3 is illegal.Example:  

POP 0E0H; Where E0H is the RAM address belonging to Register A.Operation:(direct) ← ((SP))(SP) ← (SP) – 1

3.6.38 PUSH DIRECTFunction: Push onto stackFlags: NoneDescription: This copies the indicated byte onto the stack increments SP by 1. Notice that this instruction supports only direct addressing mode. Therefore, instruction such as PUSH A, PUSH R3 is illegal.Example:    PUSH 0E0H; Where E0H is the RAM address belonging to Register A.Operation:(SP) ← (SP) + 1((SP)) ← (direct)

3.6.39 RETFunction: Return from subroutineFlags: NoneDescription: This instruction is used to return from a subroutine. RET pops the high and low-order bytes of the PC successively from the stack, decrementing the stack pointer by two. Program execution continues at the resulting address, generally the instruction immediately following an ACALL or LCALL.

3.6.40 RETIFunction: Return from interruptFlags: NoneDescription: This instruction is used to return from an interrupt service routine. RETI pops the high and low-order bytes of the PC successively from the stack, and restores the interrupt logic to accept additional interrupts at the same priority level as the one just processed. The stack pointer is left decremented by two. The PSW is not automatically restored to its pre-interrupt status. Program execution continues at the resulting address, which is generally the instruction immediately after the point at which the interrupt request was detected. If a lower or same-level interrupt is pending when the RETI instruction is executed, that one instruction will be executed before the pending interrupt is processed.

3.6.41 RL AFunction: Rotate accumulator leftFlags: NoneDescription: The eight bits in the accumulator are rotated one bit to the left. Bit 7 is rotated into the bit 0 position.Example: The accumulator holds the value 0C5H (11000101B). The instruction RL A leaves the accumulator holding the value 8BH (10001011B) with the carry unaffected.

3.6.42 RLC AFunction: Rotate accumulator left through carry flagFlags: CYDescription: The eight bits in the accumulator and the carry flag are together rotated one bit to the left. Bit 7 moves into the carry flag; the original state of the carry flag moves into the bit 0 position.Example: The accumulator holds the value 0C5H (11000101B), and the carry is zero. The instructionRLC A leaves the accumulator holding the value 8AH (10001010B) with the carry set.

3.6.43 RR AFunction: Rotate accumulator rightFlags: NoneDescription: The eight bits in the accumulator are rotated one bit to the right. Bit 0 is rotated into the bit 7 position.Example: The accumulator holds the value 0C5H (11000101B). The instruction RR A leaves the accumulator holding the value 0E2H (11100010B) with the carry unaffected.

3.6.44 RRC AFunction: Rotate accumulator right through carry flagFlags: CYDescription: The eight bits in the accumulator and the carry flag are together rotated one bit to the right. Bit 0 moves into the carry flag; the original value of the carry flag moves into the bit 7 position.Example: The accumulator holds the value 0C5H (11000101B), the carry is zero. The instructionRRC A leaves the accumulator holding the value 62H (01100010B) with the carry set.

3.6.45 SETB BITFunction: Set bitFlags: NoneDescription: SETB sets the indicated bit to one. SETB can operate on the carry flag or any directly addressable bit of a port, register, or RAM location.Example:         SETB P1.2SETB ACC.2SETB C ; carry flag CY=1

3.6.46 SJMP TARGETFunction: Short jumpFlags: NoneDescription: Program control branches unconditionally to the address indicated. The branch destination is computed by adding the signed displacement in the second instruction byte to the PC, after incrementing the PC twice. Therefore, the range of destinations allowed is from 128 bytes preceding this instruction to 127 bytes following it.Example: The label” RELADR” is assigned to an instruction at program memory location 0123H. The instruction SJMP RELADR will assemble into location 0100H. After the instruction is executed, the PC will contain the value 0123H.

3.6.47 SUBB A, SRC-BYTEFunction: Subtract with borrowFlags: OV, AC, CYDescription: SUBB subtracts the src-byte and the carry flag together from the accumulator, leaving the result in the accumulator. The steps for subtraction perform by the internal hardware of the CPU are as follows:

Take 2′s complement of the src-byte.

Add this to register A.

Invert the carry.

This instruction sets the carry flag according to the following.CYIf dest>source          0             the result is positiveIf dest=source          0             the result is 0If dest < source        1           the result is negative in 2′s complimentDifferent types of addressing modes are as follows.1. Immediate: SUBB A, #data

Example: SUBB A,#30h    ; A = A – 30H – CY2. Register: SUBB A, RnExample: SUBB A, R5     ; A = A – R5 – CY3. Direct: SUBB A,directExample: SUBB A,20H    ; A – data at (20H) – CY4. Register-indirect: SUBB A, @RiExample: SUBB A,@R1   ; A – data at (R1) – CY

3.6.48 SWAP AFunction: Swap nibbles within the accumulatorFlags: NoneDescription: SWAP A interchanges the low and high-order nibbles (four-bit fields) of the accumulator (bits 3-0 and bits 7-4). The operation can also be thought of as a four bit rotate instruction.Example:               MOV A, #25HSWAP AResult: A = 52H

3.6.49 XCH A, BYTEFunction: Exchange accumulator with byte variableFlags: NoneDescription: This instruction swaps the content of register A and the source byte. The source byte can be any register or RAM location.Example:              MOV A, #49H; A = 49HMOV R2, #30H; R2 = 30HXCH A,R2Result: A=30H, R2=49HDifferent types of addressing modes are as follows.1. Register:  XCH A, RnExample: XCH A, R52. Direct:  XCH A, directExample: XCH A, 20H3. Register-indirect: XCH A, @RiExample: XCH A,@R1

3.6.50 XCHD A,@RiFunction: Exchange digit

Flags: NoneDescription: XCHD exchanges the low-order nibble of the accumulator (bits 30), with that of the internal RAM location indirectly addressed by the specified register. The high-order nibbles (bits 7-4) of each register are not affected.Example:  R0 contains the address 20H. The accumulator holds the value 36H. Internal RAM location 20H holds the value 75H. The instruction XCHD A, @ R0 will leave RAM location 20H holding the value 76H and 35H in the accumulator.

3.6.51 XRL DEST-BYTE, SRC-BYTEFunction: Logical Exclusive OR for byte variablesFlags: NoneDescription: XRL performs the bitwise logical Exclusive OR operation between the indicated variables, storing the results in the destination.Example:               MOV A, #28HXRL A, #08HResult:   A = 20HFor XRL instruction there are total of 6 addressing modes. In four of them the accumulator must be the destination. They are as follows:1. Immediate:  XRL A, #dataExample: XRL A,#30h2. Register:  XRL A, RnExample: XRL A, R53. Direct: XRL A,directExample: XRL A,20H     ; XOR A with data in RAM location 20H4. Register-indirect: XRL A, @RiExample: XRL A,@R1   ; XOR A with data pointed by R0In the next two addressing modes the destination is direct address while the source is either A or immediate data.5. XRL direct,AExample: XRL 20H, A6. XRL direct, #dataExample: XRL 40H, #30H

CHAPTER - 4 COMPUTER AIDED INSTRUCTION

 

4.1 INTRODUCTIONIn MPS we you will be developing code for the C8051F120 EVB

(evaluation board). This board is from Silicon Laboratories (SiLabs). For that purpose, you will be using a x86 based PC (your laptop, a desktop, or co processor card in a Sun Ultra 10 workstation) to write and compile the controller programs. This type of development is called Cross Platform Development. After generating the machine code for the target environment and before you can run it you must download it to the C8051F120.

When doing cross platform development, extra knowledge of the target environment is needed. It is important to be able to answer the following questions:

• What memory resources does the execution environment have? 128 Kbytes of FLASH ROM that extends from 00000 to 1FFFFH and 8

Kbytes of RAM. The compiler - and more specifically the linker - has been configured to make use of this memory address space.

• Are we dealing with only hardware or is there an interface program we have to go through?

All communication to the C8051F120 evaluation board is currently through the IDE (integrated development environment) from Silicon Laboratories running on the PC.

The SiLabs IDE is a convenient way to edit, compile, and download source code written for the microcontroller. While SiLabs provides a nice interface for making source code changes and easily downloading them to the development boards, it lacks the actual compiler portion which converts C code to hex files, the common format used by the 8051. To do this, a free and widely used open source tool called Small Device C Compiler (SDCC) is used. SDCC compiles the C code written, and automatically optimizes and converts it to hex. Due to its popularity, support for SDCC in the SiLabs IDE comes standard, making it easy and convenient to use.

4.2 CONCEPT OF COMPILER

Compilers are programs used to convert a High Level Language to object code. Desktop compilers produce an output object code for the underlying microprocessor, but not for other microprocessors. I.E the programs written in one of the HLL like ‘C’ will compile the code to run on the system for a particular processor like x86 (underlying microprocessor in the computer). For example compilers for Dos platform is different from the Compilers for UNIX platform. 

So if one wants to define a compiler then compiler is a program that translates source code into object code. The compiler derives its name from the way it works, looking at the entire piece of source code and collecting and reorganizing the instruction. See there is a bit little difference between compiler and an interpreter. Interpreter just interprets whole program at a time while compiler analyzes and execute each line of source code in succession, without looking at the entire program.

The advantage of interpreters is that they can execute a program immediately. Secondly programs produced by compilers run much faster than the same programs executed by an interpreter. However compilers require some time before an executable program emerges. Now as compilers translate source code into object code, which is unique for each type of computer, many compilers are available for the same language.

 4.3 CONCEPT OF CROSS COMPILER

A cross compiler is similar to the compilers but we write a program for the target processor (like 8051 and its derivatives) on the host processors (like computer of x86)

It means being in one environment you are writing a code for another environment is called cross development. And the compiler used for cross development is called cross compiler

So the definition of cross compiler is a compiler that runs on one computer but produces object code for a different type of computer. Cross compilers are used to generate software that can run on computers with a new architecture or on special-purpose devices that cannot host their own compilers. Cross compilers are very popular for embedded development, where the target probably couldn't run a compiler. Typically an embedded platform has restricted RAM, no hard disk, and limited I/O capability. Code can be edited and compiled on a fast host machine (such as a PC or UNIX workstation) and the resulting executable code can then be downloaded to the target to be tested. Cross compilers are beneficial whenever the host machine has more resources (memory, disk, I/O etc) than the target.  8051 SDCC Compiler is one such

compiler that supports a huge number of host and target combinations. It supports as a target to 8 bit microcontrollers like Atmel and Motorola etc.

 4.3.1 WHY DO WE NEED CROSS COMPILER?

There are several advantages of using cross compiler. Some of them are described as follows

By using this compilers not only can development of complex embedded systems be completed in a fraction of the time, but reliability is improved, and maintenance is easy.

Knowledge of the processor instruction set is not required. A rudimentary knowledge of the 8051’s memory architecture is

desirable but not necessary. Register allocation and addressing mode details are managed by the

compiler. The ability to combine variable selection with specific operations

improves program readability. Keywords and operational functions that more nearly resemble the

human thought process can be used. Program development and debugging times are dramatically reduced

when compared to assembly language programming. The library files that are supplied provide many standard routines (such

as formatted output, data conversions, and floating-point arithmetic) that may be incorporated into your application.

Existing routine can be reused in new programs by utilizing the modular programming techniques available with C.

The C language is very portable and very popular. C compilers are available for almost all target systems. Existing software investments can be quickly and easily converted from or adapted to other processors or environments.

4.4 INSTALLING SDCC To install SDCC, follow the simple instructions below:

1. Download the latest snapshot under the Windows package with installer section. A copy can also be obtained from the course website.

2. Open the executable that was just downloaded and allow the installation wizard to step you through the process of installing SDCC on your computer. It is recommended that you leave all of the configuration options and installation paths the same as suggested by the installation wizard, so that it will be easier to assist you should problems arise.

3. To ensure SDCC was properly installed, click on: Start Menu→All Programs and ensure that SDCC shows up on your programs list. If it does, you have successfully installed SDCC.

4.5 INSTALLING SiLABS IDETo ensure SDCC was properly installed, click on: Start Menu→All

Programs and ensure that Silicon Laboratories shows up on your programs list. If it does, you have successfully installed the SiLabs IDE.

4.5.1 CONFIGURING SiLABS IDE WITH SDCC To configure SDCC as the compiler in the SiLabs IDE, follow the

instructions below:1. Click on: Start→All Programs→Silicon Laboratories→Silicon

Laboratories IDE 2. Once open, click on: Projects→Tool Chain Integration 3. You will see a Select Tool Vendor dropdown box. Select SDCC from

this menu. 4. Next, you will notice that the Assembler tab is selected by default.

Click on Browse to tell SiLabs where SDCC is installed. If you kept all the paths to the default as recommended, the path should be: C:\Program Files\SDCC\bin\asx8051.exe

5. After the assembler path is configured, you will need to configure the compiler path. To do this, click on the Compiler tab. Once again, click Browse and select the path to where SDCC is installed. If you kept all the paths to the default, the full path should be: C:\Program Files\SDCC\bin\sdcc.exe

6. Finally, to configure the linker, select the Linker tab. Click Browse and select the path where SDCC is installed. The full path for a default installation should be: C:\Program Files\SDCC\bin\sdcc.exe

7. Once you have made these changes, click OK. It is very important that you not change anything outside of what has been mentioned above, especially the command line flags passed to SDCC.

8. You have successfully set up SiLabs IDE to use SDCC!

4.6 CREATING A PROJECT 1. To create a new project, click on: Project→New. This will create an

empty project. 2. Add a new C file to the project by clicking on: Project→Add Files

to Project. Give your new file a name, such as myprog.c. 3. The file will now be part of the project, and can be compiled. Save

the project by clicking on: Project→Save Project.

4.6.1 COMPILING A PROJECT You will be using the SDCC 2.7 cross compiler. The compiler

generates executable files with the extension .exe from the C source files.

To create an executable program that runs on the C8051F120 processor from C code, there are three steps that must be taken. First the

compiler takes the C source file (.c) and creates an object file (.hex). A linker takes the object file from the compiler and adds in the language library routines to create a link file. Finally a hex converter (or loader) takes the link file and generates a downloadable executable file that can be passed to the C8051F120 by the IDE. The IDE program downloads the .out file into the C8051F120 for execution.

Fortunately there are menu items that will perform all these operations. For a C source file in an opened IDE Project, the menu commands to generate the .exe download file are:

1. To compile your project, first verify that all of your code is correct. If it’s not, don’t worry, the compiler will catch your mistakes.

2. Click on: Project→Assemble/Compile File (<Ctrl><F7> or icon) this will compile your project source code. The window at the bottom of the IDE will alert you of any errors or warnings it finds in your code. If there are errors, correct them first before moving on to the next step. If there are warnings, you may or may not want to correct them, depending on the nature of the warning.

3. Next click on: Project→Build/Make Project(<F7> or icon) This will link your compiled file. Any errors detected by the linker will be displayed.

Transferring the Executable Machine Code to the C8051F120

4. After successfully building your project, you will want to download it to the development board. Before doing this, you will need to configure the adapter used to download the source code and establish the connection. To do this, click on: Options→Connection Options Once the window opens, select the USB Debug Adapter and click OK.

5. To establish the connection to the 8051 you must click on: Debug→Connect This will connect the IDE to the development board through the USB Debug Adapter.

6. Click on: Debug→Download Object File (<Alt><D> or icon) Select the file you just compiled, and click Download. This will download the code to the development board.

4.6.2 EXECUTING THE PROGRAM ON THE C8051F120 Finally, to execute your code on the C8051F120, click on: Debug→Go

4.6.3 ASCII TERMINAL PROGRAMS We have two packages through which the C8051F120 board may

communicate with the PC using the RS232 UART ports - HyperTerminal and ProComm Plus. To begin the process, start either HyperTerminal or ProComm Plus as a dumb terminal to the EVB.

Run the program HYPERTRM.EXE from Program Files→

Accessories→ HyperTerminal.Create a new connection configured for a direct connection to COM1

(no modem) with 115200 bits per second, 8 data bits, no (none) parity, 1 stop bit, and no (none) flow control (handshaking).

Connect a DB-9 serial cable from the PC card serial port to the serial port on the EVB.

4.6.4 IDE FILE LOCATION REQUIREMENT In order to work correctly, your project files must be in the C:\

MPSfiles directory. The header files (.h) are in C:\Program Files\SDCC\include and the compiler (sdcc.exe), linker and make file (makebin.exe) are located in C:\Program Files\SDCC\bin.

4.7 PROGRAMMING HINT Normal termination of a program occurs when the last line in main() is

executed. This is done at the end of a program by calling the function: return;

at which point the program will stop but the Halt button in the IDE must still be selected.

4.8 8051 PROJECT DEVELOPMENT CYCLEThese are the steps to develop 8051 project using Keil1. Create source files in C or assembly.2. Compile or assemble source files.3. Correct errors in source files.4. Link object files from compiler and assembler.5. Test linked application.Now let us start how to work with Keil.

Compilers produce hex files that we download in to the ROM of the micro controller. The size of the hex file produced by the compiler is one of the main concerns of micro controller programmers for two reasons:

1. Micro controllers have limited on-chip ROM

2. The code space for the 8051 is limited to 64k bytes.

While assembly language produces a hex file that is much smaller than C. Programming in assembly language is tedious and time consuming. C programming, on the other hand, is less time consuming and much easier to write. One statement in C belongs to several statements in assembly language. However if we learn easily instructions we can easily deal with C programming. Some of the assembly instructions are discussed below.[5]

4.9 INSTRUCTION DEFINITIONACALL addr11Function: Absolute callDescription: ACALL unconditionally calls a subroutine located at the indicated address. The instruction increments the PC twice to obtain the address of the following instruction, then pushes the 16-bit result on to the stack(low-order byte first) and increments the stack pointer twice. The destination address is obtained by successively concatenating the five high-order bits of the incremented PC, epode bits 7-5, and the second byte of the instruction. The subroutine called must therefore start within the same 2K block of the program memory as the first byte of the instruction following ACALL. No flags are affected.

CLR AFunction: clear accumulator Description: The accumulator is cleared (all bits reset to zero). No flags are affected.

CPL AFunction: Complement accumulator. Description: Each bit of the accumulator is logically complemented (one’s complemented). Bits which previously contained a one are changed to a zero and vice-versa. No flags are affected.

DJNZ <byte>, <rel-addr>Function: Decrement and jump if not zero.Description: DJNZ decrements the location indicated by 1, and branches to the address indicated by the second operand if the resulting value is not zero. An original value of 00H wills underflow to 0FFH. No flags are affected. The branch destination would be computed by adding the signed relative-displacement value in the last instruction byte to the PC, after incrementing the PC to the firs-t byte of the following instruction. The location decremented may be a register or directly addressed byte.

JB bit,relFunction: jump if bit set Description: If the indicated bit is one, jump to the address indicated; otherwise proceed with the next instruction. The branch destination is

computed by adding the signed relative-displacement in the third instruction byte to the PC, after incrementing the PC to the first byte of the next instruction. The bit tested is not modified. No flags are affected.

JNB bit,relFunction: jump if bit not set Description: If the carry bit is zero, branch to the indicated address; otherwise proceed with the next instruction. The branch destination is computed by adding the signed relative-displacement in the third instruction byte to the PC, after incrementing the PC to the first byte of the next instruction. The bit tested is modified. No flags are affected.

LJMP addr16Function: Long jumpDescription: LJMP causes an unconditional branch to the indicated address, by loading the high order and low-order bytes of the PC (respectively) with the second and third instruction bytes. The destination may therefore be anywhere in the full 64K program memory address space. No flags are affected.

MOV <dest-byte>, <src-byte>Function: Move byte variable Description: The byte variable indicated by the second operand is copied into the location specified by the first operand. The source byte is not affected. No other register or flag is affected. This is by far the most flexible operation. Fifteen combinations of source and destination addressing modes are allowed.

RETFunction: Return from subroutineDescription: RET pops the high and low-order bytes of the PC successively from the stack, decrementing the stack pointer by two. Program execution continues at the resulting address, generally the instruction immediately following an ACALL or LCALL. No flags are affected.

SETB <bit>Function: set bit Description: SETB sets the indicated bit to one. SETB can operate on the carry flag or any directly addressable bit. No other flags are affected.

SJMP relFunction: short jump

Description: program control branches unconditionally to the address indicated. The branch destination is computed by adding the signed displacement in the second instruction byte to the PC, after incrementing the PC twice. Therefore, the range of destinations allowed is from 128 bytes preceding this instruction to 127 bytes following it.

4.9 ASSEMBLER & COMPILER Software is to be written in the assembly code in the assembler. For this project we use 8051 IDE assembler + compiler. The Various process for assembling, compiling and simulating are shown below by series of figures.

Fig 4.1 Load New File in 8051 IDE

Fig 4.2 Auto Dial Up Coding

Fig 4.3 8951 Selection

Fig 4.4 Loading Flash Buffer

4.10 SOFTWARE LOGIC OF THE PROJECT

MAIN:

KEYCHECK: JNB P3.0,OK JNB P3.4,WRONG JNB P3.5,WRONG JNB P3.7,WRONG JNB P3.1,WRONG JNB P3.2,WRONG JNB P3.3,WRONG SJMP KEYCHECK

OK: ACALL DELAY1 ; JNB P3.0,WRONG JNB P3.1,OK1; JNB P3.2,WRONG; JNB P3.3,WRONG JNB P3.4,WRONG JNB P3.5,WRONG JNB P3.7,WRONG SJMP OK

OK1: JNB P3.0,WRONG JNB P3.1,WRONG JNB P3.2,OK2 JNB P3.3,WRONG JNB P3.4,WRONG JNB P3.5,WRONG JNB P3.7,WRONG SJMP OK1

OK2: JNB P3.2,$ ACALL DELAY

; JNB P3.0,WRONG; JNB P3.1,WRONG; JNB P3.2,WRONG JNB P3.3,OK3 JNB P3.4,WRONG JNB P3.5,WRONG JNB P3.7,WRONG

OK3: CLR P1.3 ; BUZZER CLR P1.0 SETB P1.1 ACALL DELAY1 SETB P1.3 ; BUZZER OFF SETB P1.0 SETB P1.1

ACALL DELAY1 SETB P1.0 CLR P1.1 ACALL DELAY1 SETB P1.0 SETB P1.1 LJMP MAIN

DELAY1: MOV R3,#00 MOV R2,#00 MOV R1,#12 DELAY: DJNZ R3,DELAY DJNZ R2,DELAY DJNZ R1,DELAY RET

WRONG:

ACALL DELAY CLR BUZ CLR RELAY ACALL DELAY SETB RELAY ACALL DELAY CLR RELAY ACALL DELAY SETB RELAY

In the Gas sensor, we use IC 555 along with sensor as a main component. Pin no 4 and pin no 8 is connected to the positive supply. Pin no 1 is connected to the negative voltage. One capacitor is grounded from the pin no 5 for noise cancellation. Output is available on the pin no 3. Sensor is connected to the pin no 2. In the case of Gas sensor, Pin no 2 is negative bias through the 33k ohm resistor and pin no 3 is positively biased. Infrared LED is directly connected to the positive and negative supply through the 470 ohm resistor.

Fig 4.5 Gas Sensor with MCU

In normal stage when Gas is detected by sensor then pin no 2 is positively biased. If pin no 2 is positive then negative output is available on the pin no 3. Now when gas concentration rises then pin no. 2 is now gets its voltage from only 33 k ohm resistor. If pin no 2 is become negative then output is shifted to the pin no 3. When positive output is available on the pin no 3 and with the help of this voltage NPN transistor is ON and NPN transistor provide a negative voltage as a pulse to the microcontroller. Microcontroller allows the auto dial up using the relay and starts an exhaust fan to fan out excess gas concentration. It also allows sending an ON signal to APR 9600

which will start to play recording message in few seconds for Gas. In that mid time hands free dials last redialed number of the mobile phone which provides info to the concerned people.

In the case of Fire sensor, we use IC 555 along with Heat sensor as a main component. Pin no 4 and pin no 8 is connected to the positive supply. Pin no 1 is connected to the negative voltage. One capacitor is grounded from the pin no 5 for noise cancellation. Output is available on the pin no 3. Sensor is connected to the pin no 2. In the heat sensor, Pin no 2 is negative bias through the 33k ohm resistor and pin no 3 is positively biased. Infrared LED is directly connected to the positive and negative supply through the 470 ohm resistor.

Fig 4.6 Fire Sensor with MCU

In normal stage heat is detected by sensor then pin no 2 is positively biased. If pin no 2 is positive then negative output is available on the pin no 3. Now when temperature rises above the nominal room temperature then pin no. 2 is now gets its voltage from only 33 k ohm resistor. If pin no 2 is become negative then output is shifted to the pin no 3. When positive output is available on the pin no 3 and with the help of this voltage NPN transistor is ON and NPN transistor provide a negative voltage as a pulse to the microcontroller. Microcontroller allows the auto dial up using the relay and it also allows sending an ON signal to APR 9600 which will start to play recording message in few seconds for Gas. In that mid time hands free dials last redialed number of the mobile phone which provides info to the concerned people. Note that exhaust fan will remain in its idle state of OFF in case of heat/fire detection & prevention. Note that microcontroller sense only negative input to the microcontroller.

CHAPTER - 5 APR9600 RE-RECORDING VOICE IC

5.1 APR 9600Digital voice processing chips with different features and coding

techniques for speech compression and processing are available on the market from a number of semiconductor manufacturers. Advanced chips such as Texas instruments’ TMS320C31 can implement various voice-processing algorithms including code-excited linear prediction, adaptive differential pulse-code modulation, A law (specified by California Council for International Trade), μ law (specified by Bell Telephone) and vector sum-excited linear prediction. On the other hand, APR9600 single chip voice recorder and playback device from Aplus Integrated Circuits makes use of a proprietary analogue storage technique implemented using flash nonvolatile memory process in which each cell is capable of storing up to 256 voltage levels. This technology enables the APR9600 to reproduce voice signals in their natural form. The APR9600 is a good standalone voice recorder or playback IC with nonvolatile storage and playback capability for 5 to 60 seconds. It can record and play multiple messages at random or in sequential mode. The user can select sample rates with consequent quality and recording time trade-off. Microphone amplifier, automatic gain control (AGC) circuits, internal anti-aliasing filter, integrated output amplifier and messages management are some of the features of the APR9600 chip.

5.1.2 FEATURES Single-chip, high-quality voice recording & playback solution No external ICs required Minimum external components Non-volatile Flash memory technology No battery backup required User-Selectable messaging options Random access of multiple fixed-duration messages Sequential access of multiple variable-duration messages User-friendly, easy-to-use operation Programming & development systems not required Level-activated recording & edge-activated play back switches Low power consumption

Operating current: 25 mA typical Standby current: 1 uA typical Automatic power-down Chip Enable pin for simple message expansion

5.2 GENERAL DESCRIPTIONThe APR9600 device offers true single-chip voice recording, non-

volatile storage, and playback capability for 5 to 60 seconds. The device supports both random and sequential access of multiple messages. Sample rates are user-selectable, allowing designers to customize their design for unique quality and storage time needs. Integrated output amplifier, microphone amplifier, and AGC circuits greatly simplify system design. The device is ideal for use in portable voice recorders, toys, and many other consumer and industrial applications.

APLUS integrated achieves these high levels of storage capability by using its proprietary analog/multilevel storage technology implemented in an advanced Flash non-volatile memory process, where each memory cell can store 256 voltage levels. This technology enables the APR9600 device to reproduce voice signals in their natural form. It eliminates the need for encoding and compression, which often introduce distortion.

5.3 FUNCTIONAL DESCRIPTIONAPR9600 block diagram is included in order to describe the devices

internal architecture. At the left hand side of the diagram are the analog inputs. A differential microphone amplifier, including integrated AGC, is included on-chip for applications requiring use. The amplified microphone signals fed into the device by connecting the ANA_OUT pin to the ANA_IN pin through an external DC blocking capacitor. Recording can be fed directly into the ANA_IN pin through a DC blocking capacitor, however, the connection between ANA_IN and ANA_OUT is still required for playback. The next block encountered by the input signal is the internal anti-aliasing filter. The filter automatically adjusts its response according to the sampling frequency selected so Shannon’s Sampling Theorem is satisfied. After anti-aliasing filtering is accomplished the signal is ready to be clocked into the memory array. This storage is accomplished through a combination of the Sample and Hold circuit and the Analog Write/Read circuit. These circuits are clocked by either the Internal Oscillator or an external clock source. When playback is desired the previously stored recording is retrieved from memory, low pass filtered, and amplified as shown on the right hand side of the diagram. The signal can be heard by connecting a speaker to the SP+ and SP- pins. Chip-

wide management is accomplished through the device control block shown in the upper right hand corner. Message management is provided through the

Fig 5.1 Pin Diagram of APR 9600 IC

message control block represented in the lower center of the block diagram. More detail on actual device application can be found in the Sample Application section. More detail on sampling control can be found in the Sample Rate and Voice Quality section. More detail on Message management and device control can be found in the Message Management section.

5.4 MESSAGE MANAGEMENT

5.4.1 MESSAGE MANAGEMENT GENERAL DESCRIPTIONPlayback and record operations are managed by on-chip circuitry. There

are several available messaging modes depending upon desired operation. These message modes determine message management style, message length, and external parts count. Therefore, the designer must select the appropriate operating mode before beginning the design. Operating modes do not affect voice quality; for information on factors affecting quality refer to the Sampling Rate & Voice Quality section. The device supports five message management modes (defined by the MSEL1, MSEL2 and /M8_OPTION pins shown in Figures 1 and 2):

Figure 5.2 APR9600 Block Diagram Random access mode with 2, 4, or 8 fixed-duration messages Tape mode, with multiple variable-duration messages, provides two

options:- Auto rewind- Normal

Modes cannot be mixed. Switching of modes after the device has recorded an initial message is not recommended. If modes are switched after an initial recording has been made some unpredictable message fragments from the previous mode may remain present, and be audible on playback, in the new mode. These fragments will disappear after a Record operation in the newly selected mode. Table 1 defines the decoding necessary to choose the desired mode.

An important feature of the APR9600 Message management capabilities is the ability to audibly prompt the user to change in the device's status through the use of "beeps" superimposed on the device's output. This feature is enabled by asserting a logic high level on the BE pin.

Table 5.1 Mode selection

5.4.2 RANDOM ACCESS MODERandom access mode supports 2, 4, or 8 Message segments of fixed

duration. As suggested recording or playback can be made randomly in any of the selected messages. The length of each message segment is the total recording length available (as defined by the selected sampling rate) divided by the total number of segments enabled (as decoded in Table1). Random access mode provides easy indexing to message segments.

5.4.2.1 FUNCTIONAL DESCRIPTION OF RECORDING IN RANDOM ACCESS MODE

On power up, the device is ready to record or playback in any of the enabled message segments. To record,/CE must be set low to enable the device and /RE must be set low to enable recording. You initiate recording by applying a low level on the message trigger pin that represents the message segment you intend to use. The message trigger pins are labeled /M1_MESSAGE - /M8_OPTION on pins 1-9 (excluding pin 7) for message segments 1-8 respectively. Note: Message trigger pins of M1_MESSAGE,/M2_NEXT, /M7_END, and /M8_OPTION, have expanded names to represent the different functionality that these pins assume in the other modes. In random access mode these pins should be considered purely message trigger pins with the same functionality as /M3, /M4, /M5, and /M6. For a more thorough explanation of the functionality of device pins in different modes please refer to the pin description table that appears later in this document. When actual recording begins the device responds with a single beep (if the BE pin is high to enable the beep tone) at the speaker outputs to indicate that it has started recording. Recording continues as long as the message pin stays low. The rising edge of the same message trigger pin during record stops the recording operation (indicated with a single beep).If the message trigger pin is held low beyond the end of the maximum allocated duration, recording stops automatically (indicated with two beeps), regardless of the state of the message trigger pin. The chip then enters low-power mode until the message trigger pin returns high. After the message trigger pin returns to high, the chip enters standby mode. Any subsequent high to low transition on the same message trigger pin will initiate recording from the beginning of the same message segment. The entire previous message is then overwritten by the new message, regardless of the duration of the new message. Transitions on any other message trigger pin or the /RE pin during the record operation are ignored until after the device enters standby mode.

5.4.2.2 FUNCTIONAL DESCRIPTION OF PLAYBACK RANDOM ACCESS MODE

On power up, the device is ready to record or playback, in any of the enabled message segments. To playback,/CE must be set low to enable the device and RE must be set high to disable recording & enable playback. You initiate playback by applying a high to low edge on the message trigger pin that represents the message segment you intend to playback. Playback will continue until the end of the message is reached. If a high to low edge occurs on the same message trigger pin during playback, playback of the current message stops immediately. If a different message trigger pin pulses during playback, playback of the current message stops immediately (indicated by one beep) and playback of the new message segment begins. A delay equal to 8,400 cycles of the sample clock will be encountered before the device starts playing the new message. If a message trigger pin is held low, the selected message is played back repeatedly as long as the trigger pin stays low. A period of silence, of duration equal to 8,400 cycles of the sampling clock, will be inserted during looping as an indicator to the user of the transition between the end and the beginning of the message.

5.4.3 TAPE MODETape mode manages messages sequentially much like traditional

cassette tape recorders. Within tape mode two options exist, auto rewind and normal. Auto rewind mode configures the device to automatically rewind to the beginning of the message immediately following recording or playback of the message. In tape mode, using either option, messages must be recorded or played back sequentially, much like a traditional cassette tape recorder

5.4.3.1 FUNCTION DESCRIPTION OF RECORDING IN TAPE MODE USING THE AUTO REWIND OPTION

On power up, the device is ready to record or playback, starting at the first address in the memory array. To record, /CE must be set low to enable the device and /RE must be set low to enable recording. A falling edge of the /M1_MESSAGE pin initiates voice recording (indicated by one beep).A subsequent rising edge of the /M1_MESSAGE pin during recording stops the recording (also indicated by one beep). If the M1_MESSAGE pin is held low beyond the end of the available memory, recording will stop automatically (indicated by two beeps). The device will then assert a logic low on the /M7_END pin until the /M1 Message pin is released. The device returns to standby mode when the /M1_MESSAGE pin goes high again. After recording is finished the device will automatically rewind to the beginning of the most recently recorded message and wait for the next user input. The auto rewind

function is convenient because it allows the user to immediately playback and review the message without the need to rewind. However, caution must be practiced because a subsequent record operation will overwrite the last recorded message unless the user remembers to pulse the /M2_Next pin in order to increment the device past the current message. A subsequent falling edge on the /M1_Message pin starts a new record operation, overwriting the previously existing message. You can preserve the previously recorded message by using the /M2_Next input to advance to the next available message segment. To perform this function, the /M2_NEXT pin must be pulled low for at least 400 cycles of the sample clock. The auto rewind mode allows the user to record over the just recorded message simply by initiating a record sequence without first toggling the /M2_NEXT pin. To record over any other message however requires a different sequence. You must pulse the /CE pin low once to rewind the device to the beginning of the voice memory. The /M2_NEXT pin must then be pulsed low for the specified number of times to move to the start of the message you wish to overwrite. Upon arriving at the desired message a record sequence can be initiated to overwrite the previously recorded material. After you overwrite the message it becomes the last available message and all previously recorded messages following this message become inaccessible. If during a record operation all of the available memory is used, the device will stop recording automatically,(double beep) and set the /M7_END pin low for a duration equal to 1600 cycles of the sample clock. Playback can be initiated on this last message, but pulsing the /M2_Next pin will put the device into an "overflow state". Once the device enters an overflow state any subsequent pulsing of /M1_MESSAGE or /M2_NEXT will only result in a double beep and setting of the /M7_END pin low for a duration equal to 400 cycles of the sample clock. To precede from this state the user must rewind the device to the beginning of the memory array. This can be accomplished by toggling the /CE pin low or cycling power. All inputs, except the /CE pin, are ignored during recording.

5.4.3.2 FUNCTION DESCRIPTION OF PLAYBACK IN TAPE MODE USING AUTO REWIND OPTION

On power-up, the device is ready to record or playback, starting at the first address in the memory array. Before you can begin playback, the /CE input must be set to low to enable the device and /RE must be set to high to disable recording and enable playback. The first high to low going pulse of the /M1_MESSAGE pin initiates playback from the beginning of the current message; on power up the first message is the current message. When the /M1_MESSAGE pin pulses low the second time, playback of the current Message stops immediately. When the /M1_MESSAGE pin pulses low a third time, playback of the current message starts again from its beginning. If you

hold the /M1_MESSAGE pin low continuously the same message will play continuously in a looping fashion. A 1,540ms period of silence is inserted during looping as an indicator to the user of the transition between the beginning and end of the message. Note that in auto rewind mode the device always rewinds to the beginning of the current message. To listen to a subsequent message the device must be fast forwarded past the current message to the next message. This function is accomplished by toggling the /M2_NEXT pin from high to low. The pulse must be low for least 400 cycles of the sampling clock. After the device is incremented to the desired message the user can initiate playback of the message with the playback sequence described above. A special case exists when the /M2_NEXT pin goes low during playback. Playback of the current message will stop, the device will beep, advance to the next message and initiate playback of the next message. (Note that if /M2 Next goes low when not in playback mode, the device will prepare to play the next message, but will not actually initiate playback).

If the /CE pin goes high during playback, playback of the current message will stop, the device will beep, reset to the beginning of the first message, and wait for a subsequent playback command. When you reach the end of the memory array, any subsequent pulsing of /M1_MESSAGE or /M2_NEXT will only result in a double beep. To precede from this state the user must rewind the device to the beginning of the m memory array. This can be accomplished by toggling the /CE pin low or cycling power.

5.4.3.3 FUNCTIONAL DESCRIPTION OF RECORDING IN TAPE MODE USING THE NORMAL OPTION

On power-up, the device is ready to record or playback, starting at the first address in the memory array. Before you can begin recording, the /CE input must be set to low to enable the device and /RE must be set to low to enable recording. On a falling edge of the /M1_MESSAGE pin the device will beep once and initiate recording. A subsequent rising edge on the /M1 Message pin will stop recording and insert a single beep. If the /M1_ MESSAGE pin is held low beyond the end of the available memory, recording Stops automatically, and two beeps are inserted; regardless of the state of the /M1_MESSAGE pin. The device returns to the standby mode when the /M1_MESSAGE pin is returned high. A subsequent falling edge on the /M1_MESSAGE pin starts a new record operation in the memory array immediately following the last recorded message, thus preserving the last recorded message. To record over all previous messages you must pulse the /CE pin low once to reset the device to the beginning of the first message. You can then initiate a record sequence, as described above, to record a new message. The most recently recorded message will become the last recorded

message and all previously recorded messages following this message will become inaccessible. If you wish to preserve any current messages it is recommend that the Auto Rewind option be used instead of the Normal option. If the Normal option is necessary the following sequence can be used. To preserve current messages you must fast forward past the messages you want to keep before you can record a new message. To fast forward when using the Normal option you must switch to play mode and listen to messages sequentially until you arrive at the beginning of the message you wish to overwrite. At this stage you should switch back to record mode and overwrite the desired message. The most recently recorded message will become the last recorded message and all previously recorded messages following this message will become inaccessible. All inputs, except /CE, are ignored during recording.

5.4.3.4 FUNCTIONAL DESCRIPTION OF PLAYBACK IN TAPE MODE USING THE NORMAL OPTION

On power-up or after a low to high transition on /RE the device is ready to record or playback starting at the first address in the memory array. Before you can begin playback of messages, the /CE input must be set to low to enable the device and /RE must be set to high to enable playback. The first high to low going pulse of the /M1_MESSAGE pin initiates playback from the beginning of the current message. When the /M1_MESSAGE pin pulses from high to low a second time, playback of the current message stops immediately. When the /M1_MESSAGE pin pulses from high to low a third time, playback of the next message starts again from the beginning. If you hold the /M1_MESSAGE pin low continuously, the current message and subsequent messages play until the one of the following conditions is met: the end of the memory array is reached, the last message is reached, the /M1_message pin is released. If the last recorded message has already played, any further transitions on the /M1_MESSAGE pin will initiate a double beep for warning and the /M7_END pin will go low. To exit this state you must pulse the /CE pin high and then low once during standby to reset the pointer to the beginning of the first message.

Fig 5.3 APR9600 Experimental board

5.5 MICROPROCESSOR CONTROLLED MESSAGE MANAGEMENT

The APR9600 device incorporates several features design help simplify microprocessor controlled message management When controlling messages the microprocessor essentially toggles pins as described in the message management sections described previously. The /BUSY, /STROBE, and /M7_END pins are included to simplify handshaking between the microprocessor and the APR9600.The /BUSY pin, when low, indicates to the host processor that the device is busy and that No commands can be accepted. When this pin is high the device is ready to accept and execute commands from the host. The /STROBE pin pulses low each time a memory segment is used. Counting pulses on this pin enables the host processor too accurately determine how much recording time has been used, and how much recording time remains. The APR9600 has a total of eighty memory segments. The /M7_END pin is used as an indicator that the device has stopped its current record or playback operation. During recording a low going pulse indicates that all memory has been used. During playback a low pulse indicates that the last message has played. Microprocessor control can also be used to link several APR9600 devices together in order to increase total available recording time. In this application both the speaker and microphone signals can be connected in parallel. The microprocessor will then control which device currently drives the speaker by enabling or disabling each device using its respective /CE pins. A continuous message cannot be recorded in multiple devices however because the transition from one device to the next will incur a delay that is noticeable upon playback. For this reason it is recommended that message boundaries and device boundaries always coincide.

5.6 SIGNAL STORAGEThe APR9600 samples incoming voice signals and stores the

instantaneous voltage samples in non-volatile FLASH memory cells. Each memory cell can support voltage ranges from 0 to 256 levels. These 256 discrete voltage levels are the equivalent of 8-bit (28=256) binary encoded values. During playback the stored signals are retrieved from memory, smoothed to form a continuous signal, and then amplified before being fed to an external speaker.

5.7 SAMPLING RATE & VOICE QUALITYAccording to Shannon's sampling theorem, the highest possible

frequency component introduced to the input of a sampling system must be equal to or less than half the sampling frequency if aliasing errors are to be eliminated. The APR9600 automatically filters its input, based on the selected sampling frequency, to meet this requirement. Higher sampling rates increase the bandwidth and hence the voice quality, but they also use more memory cells for the same length of recording time. Lower sampling rates use fewer memory cells and effectively increase the duration capabilities of the device, but they also reduce incoming signal bandwidth. The APR9600 accommodates sampling rates as high as 8 kHz and as low as 4 kHz. You can control the quality/duration trade off by controlling the sampling frequency. An internal oscillator provides the APR9600 sampling clock. Oscillator frequency can be changed by changing the resistance from the OscR pin to GND. Table 5.2 summarizes resistance values and the corresponding sampling frequencies, as well as the resulting input bandwidth and duration.

Resistance(k ohm)

SamplingFrequency(kHz)

InputBandwidth (kHz)

Duration(sec)

84 4.2 2.1 60

38 6.4 3.2 40

34 8 4 32

Table 5.2 Input Bandwidth & Duration

5.8 AUTOMATIC GAIN CONTROL (AGC)The APR9600 device has an integrated AGC. The AGC affects the

microphone input but does not affect the ANA_IN input. The AGC circuit insures that the input signal is properly amplified. The AGC works by applying maximum gain to small input signals and minimum gain to large input signals. This assures that inputs of varying amplitude are recorded at the optimum signal level. The AGC amplifier is designed to have a fast attack time and a slow decay time. This timing is controlled by the RC network connected to pin 19. A value of 220K and 4.7uF has been found to work well for the English language. Be aware that different languages, speakers from different countries, and music may all require modification of the recommended values for the AGC RC network.

5.11 SAMPLING APPLICATION The following reference schematics are included as examples of how a

recording system might be designed. Each reference schematic shows the device incorporated in one of its three main modes: Random Access, Tape mode – Normal option, and Tape mode – Auto Rewind option. Note that in several of the applications either one or all of the /BUSY, /STROBE, or /M7_END pins are connected to LEDs as indicators of device status. This is possible because all of these pins and signals were designed to have timing compatible with both microprocessor interface and manual LED indication. A bias must be applied to the electrets microphone in order to power its built-in circuitry. The ground return of this bias network is connected to the /Busy. This configuration saves power when record mode. Both pins 18 and 19, MicIn and MicRef, must be AC coupled to the microphone network in order to block the DC biasing voltage. Figure 3 shows the device configured in random access mode. The device is using eight Message segments, the maximum available, in this mode. Note that message trigger pins that are not used, for modes with less than eight segments, can be left unconnected with the exception of pin /M8_OPTION which should be pulled to VCC through a 100k resistor.

5.10 FIGURES OF MODES

Figure 5.4 Tape Mode, Normal Option

Figure 5.5 Tape Mode, Auto Rewind Option

Figure 5.6 Random Access Mode

5.11 PIN DESCRIPTION

Table 5.3 Pin Description of APR 9600

Table 5.3 shows the Pin Description & Functionality of APR 9600 in different modes.

5.12 ELECTRICAL CHARACTERISTICSThe following table 5.4 , 5.5, 5.5 list Absolute Maximum Ratings, DC

Characteristics, and Analog Characteristics for the APR9600 device.

Table 5.4 Absolute Maximum Ratings

Table 5.5 DC Characteristics

Table 5.6 Analog Characteristics

5.13 APPLICATION TIPSTIPS FOR BETTER SOUND REPLAY QUALITY

Use a good quality 8 Ohm speaker with a cavity such as speakers for computer sound systems. Do not use a bare speaker which gives you degraded sound.

For better sound replay quality, speak with a distance to the on-board microphone and speak clearly. Also keep the background noise as low as possible.

For even better sound replay quality, use microphone input or Audio Line In input. If Audio Line In is used, the amplitude of input signal should be < 100 mV p-p.

CHAPTER - 6 CONCLUSION AND FUTURE ENHANCEMENT

6.1 CONCLUSIONSensor technologies are developing fast with time and innovative

technology. This field is one of the most interesting areas to be discovered continuously. So many new sensor designs will come out and develop in future hence increasing the competitiveness between researchers. This project is a minor contribution to instill the interest of people. It also gives a very basic understanding which will be a good learning process to the beginner. The hardware and software part of this project is working based on the objectives mentioned before and based on the conduct test or experiments held towards the end this project, the results are stable and working as it should be. This project can be concluded that the target to develop the security system basedGSM has achieved. GSM technology capable solution has proved to be controlled remotely, provide home security and is cost effective as compared to the previously existing systems without Gas sensor and Fire sensor in one product or circuit.

The security is what a person expects from a home, this project was designed keeping this particular aspect in mind. The security system is made fool proof to the maximum extent possible. In this project we make use of a microcontroller as the main controller to control the input and the output that reach the controller. There is a large scope in the future enhancements that can be provided along with this project like actuating a fire detection alarm or sensing a leakage of gas etc.

We conclude that we have 100% successfully fulfilled our project and we have confidence that our project will provide full security for Industries, Hotels, Restaurants, Homes. Hence we can conclude that the required goals and objectives of Interactive Dial up based Home Security System have been achieved. The security system with 3 combinations function has been implemented. This project will benefit all the people in monitoring their property even when they are away from home with low cost of home security system. It is most advantageous as compared to other alternatives available for providing security since it is an integrated system. In this project security plays an important role with low cost and with many advantages. The system is simple, secure, reliable and fast. It can be operated by anyone who knows nothing about its software and effective.

So, our project will help a lot everywhere because of its security and alertness. We will still develop and extend our project to maximum level to safeguard the places and extend the service with good response.

6.2 RESULTThis project is microcontroller based project. A Gas sensor is used to

detect dangerous gas leaks in the home kitchen, large scale industries, manufacturing plants, skyscrapers, lodge, hotels etc. Mainly since it’s a small unit we can ideally implement to detect dangerous gas leaks in the kitchen. For large scale, we have to implement complex circuitry with same logic. The sensor can also sense LPG leak in your car or in a service station, storage tank environment. This unit can be easily incorporated into an alarm unit, to sound an alarm. The sensor has excellent sensitivity combined with a quick response time. When GAS leakage is detected above 8 ppm, the sensor sends electrical signal to microcontroller which in turn sends ON signal exhaust fan, alarm, auto dial up and APR. So the four systems start working simultaneously to enhance security & preserve accidents. First the exhaust fan will start that will try to reduce the concentration of the gas so that any incident can be avoided; secondly the alarm will start and will warn the people of surrounding areas. Lastly, the auto dial up will start working and will call to the to the authorized person using cellular network called GSM specifically to the last called number or stored number of the mobile telephony, and lastly the APR with the help of speaker will give the message of gas leakage to the called person.

Another feature that we added to our project is a fire sensor. A fire sensor will start working in case if there occurred fire due to some sparking or blazes elements present there, then fire sensor will do the same work as done by gas sensor. It will send signals to the microcontroller which in turn will give signal to alarm and the alarm will start. Also it will give signal to the APR and auto dial up system. The auto dial up system as said above will call the last caller and the speaker connected to APR will give the message about the fire.

6.3 LIMITATION

Only Detection, not BlockageThe major limitation of the project is that it can only detect the gas leakage

and can alert about it but it can’t stop the leakage.

High Sensitivity of Heat SensorThe fire sensor that we used is highly sensitive, in case of normal heat in

the kitchen or industry it will start working and alarm will be on.

Beside these limitations there are some limitations of gas sensor used. There are some conditions that must be prohibited while using gas sensor. They are as follows:

Exposure to Organic Silicon Steam

Organic silicon steam cause sensors invalid, sensors must be avoid exposing to silicon bond, fixture, silicon latex, putty or plastic contain silicon environment.

High Corrosive Gas

If the sensors exposed to high concentration corrosive gas (such as H2Sz, SOXCl2, HCl etc), it will not only result in corrosion of sensors structure, also it cause sincere sensitivity attenuation.

Alkali, Corrosive Alkali Metals Salt, Halogen Pollution

The sensors performance will be changed badly if sensors be sprayed polluted by alkali metals salt especially brine, or be exposed to halogen such as florin.

Touch Water

Sensitivity of the sensors will be reduced when spattered or dipped in water.

Freezing

Do avoid icing on sensor’s surface, otherwise sensor would lose sensitivity. Applied Voltage Higher

Applied voltage on sensor should not be higher than stipulated value, otherwise it cause down-line or heater damaged, and bring on sensors’ sensitivity characteristic changed badly.

6.4 FUTURE SCOPE A relay contact may be used to operate a camera when it detects an

intruder which helps in finding the intruder’s identity easily. As the system is flexible to dial any previously stored number, this

system can be used in any places wherever security is needed like industries, hotels, houses, and shops, restaurants etc.

A more advancement can be brought to the system using the computer control, so the entire process can be analyzed effectively.

By adding LCD display and with slight changes, we can update information, which was dumped in microcontroller.

Entry faces identification with web camera. A water sprinkling system can also be connected to it. More dial up option up to 25 last redial list are available which can

be implemented for better security results.

BIBLIOGRAPHY

[1] Adel S. Sedra, Kenneth Carless Smith, “Microelectronic Circuits, Volume 1, Oxford University Press, 2004

[2] Muhammad Ali Mazidi, Rolin McKinley, Janice Gillispie Mazidi, “The 8051 Microcontroller and Embedded Systems Using Assembly and C”, Second edition, Pearson Education India, 2007

[3] U.A.Bakshi and A.P.Godse, “Linear Integrated Circuits”, Technical Publications Pune™, First Edition 2010.

[4] M. Gopal, I.J. Nagrath, “Control Systems Engineering” 4/e, New Age Publications (Academic), India

[5] Dogan Ibrahim, “Microcontroller Projects in C for the 8051”, Newnes (June 2000)

[6] “Datasheet Catalog”, www.datasheetcatalog.com

[7] “All Datasheet”, www.all datasheet .com/

[8] “Fairchild Semiconductor®”, www.fairchildsemi.com

[9] “Atmel Technology”, http://www.atmel.com/

[10] “Electronic for You”, www.electronicsforu.com

[11] “How Stuff Works”, http://www.howstuffworks.com

[12] “Aplus Integrated Circuit Inc.”, http://www.aplusinc.com.tw/

[13] “Google Books”, books.google.co.in