Project Reportprathi Block Diagram

7/31/2019 Project Reportprathi Block Diagram

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DATA ACQUISITION 1

ABSTRACT

Data Acquisition using RF communication has two mainfunctional aspects: measurement & communication. This projectfocuses on developing an embedded system to extract temperature datafrom an temperature sensor, display the instantaneous value on LCD andthe same data is transmitted over a distant place using RF(Zigbee)communication.

This project consists of two parts. One is transmitter sectionwhich is built around microcontroller based 16F877A architecture, ADC,Sensors to measure temperature & smoke and a Zigbee transceiver totransmit data. On the other hand receiver consists of Zigbee transceiver to

receive the data and display the data on the LCD display. Instantaneousdata of temperature is displayed on LCD and Buzzer indication is provided iftemperature is more than 400 or smoke is detected.


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DATA ACQUISITION 2

ACKNOWLEDGEMENT

It gives us immense pleasure to express our deep sense of

gratitude to the people who have helped and supported us throughout

the course and the process of completion of this project.

We would like to take this opportunity to thank Dr

B.G.Sangameshwara, Principal, SJCE for providing a healthy

environment in college and for extending the facilities to carry out the

project work.

We owe a special thanks to our Internal guide Asst. Prof

S.Gopalakrishna. His guidance and encouragement has helped up

leaps and bounds in completing this project. He has constantly

reviewed our project and gave us various suggestions for

implementing and enhancing our project. He has also guided us in

preparing our report by providing us with various other details needed

in completing our report.

We would like to thank our family members and friends for

morally encouraging us in everything we do.

Project associates

Prathima Baliga J.P.

Savitha.R

Raghavendra Shenoy


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DATA ACQUISITION 3

CONTENTS

CHAPTER 1:

INTRODUCTION

1.1 WHAT IS DATA

AQUASITION ?........................................................................6

1.2 NEED OF WIRELESS DATA

AQUASITION.6

1.3 MAJOR COMPONENTS WHEN BUILDING A DATA ACQUISITION

SYSTEM6

CHAPTER 2:

BASIC PRINCIPLES

2.1 BASIC PRINCIPLES OF DATA ACQUISITION USING

RF7

2.2 BLOCK

DIAGRAM

..9

CHAPTER 3:

PERIPHERALS

3.1 POWER

SUPPLY

.12

3.2 RS

23212


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DATA ACQUISITION 4

3.3 TEMPERATURE

SENSOR................14

3.4 SMOKE

DETECTOR

..16

3.5 BUZZER

.17

3.6 DOT MATRIX

LCD

.18

3.7 MICROCANTROLLER

.18

CHAPTER 4:

RF COMMUNICATION

4.1 ZIGBEE

4.1.1 Characteristics of

Zigbee20

4.1.2 Network topologies supported by

Zigbee21

4.1.3

ARCITECTURE...22

4.1.4 Types of

traffic..23

4.1.5 Block diagram of Zigbee

Transceiver24

4.2 Type of

modulation

25


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DATA ACQUISITION 5

CHAPTER 5:

HARDWARE IMPLEMENTATION

5.1 Sensor & TX schematic....29

5.2 RF

receiver

..32

CHAPTER 6:

FIRMWARE LOGIC

6.1Flow chart of Data acquisition using RF

...33

CHAPTER 7:

SOFTWARE

7.1MPLAB IDE V8.60.35

7.2STEPS IN DEVELOPING A

PROGRAM.36

CHAPTER 8:

ADVANTAGES , APPLICATIONS & LIMITATIONS

8.1

ADVANTAGES

37


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DATA ACQUISITION 6

8.2

APPLICATIONS

..37

8.3

RESULTS.37

CHAPTER 9:

DEVELOPMENT & RESULTS

9.1 DEVELOPMENT

STEPS 38

9.2

RESULTS

.. .38

APPENDIX:

10. CONCLUSION

.40

11. FUTURE

SCOPE..

40

12.

REFERENCE

..40


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DATA ACQUISITION 7

CHAPTER 1 - INTRODUCTION

1.1 WHAT IS DATA ACQUISITION?

Data acquisition involves gathering signals from

measurements sources and digitalizing the signal for storage analysis

and presentation on PC or LCD. Data acquisition systems come inmany PC technology forms to offer flexibility. Here we used RF

communication to acquire data and explained in detail in next

chapters.

1.2 NEED OF WIRELESS DATA AQUASITION

In an industry during certain hazards it will be very

difficult to monitor the parameter through wires and analog devicessuch as transducers. To overcome this we use wireless devices tomonitor the parameter and so that we can take certain steps in worstcase.

Few years back the use of wireless devices was very lessbut due to rapid development in technology nowadays maximum ofour data transfer is through wireless.

1.3 MAJOR COMPONETS WHEN BUILDING A BASIC

DATA

ACQUISITION SYSTEM

We need to consider the following five components when

building a basic data acquisition system.

Transducers and sensors

Signals


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DATA ACQUISITION 8

Signal conditioning

DAQ hardware

Driver and display

FIG-1.1. Basic diagram of data acquisition and display.

CHAPTER 2 - BASIC PRINCIPLES

2.1 BASIC PRINCIPLE OF DATA ACQUISITIONUSING RF

DATA AQUASITION USING RF consists of following

blocks.

Temperature sensor

Smoke sensor

Microcontroller

LCD displays

Power supply

Buzzer indication

RF (Zigbee) communication module.

This system senses the temperature and smoke and

continuously and send data to Microcontroller. Controller PIC16F877

consists of ADC where it converts analog signal to digital and send toLCD input and UART.


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DATA ACQUISITION 9

Zigbee is RF transceiver module of 2.4GHZ is connected to

UART of controller where the data is sent to distance place

In the receiver side the data is picked by the Zigbee transceiver

and send to UART receiver of Microcontroller. Microcontroller will

compares the data with reference temperature value. It displays thedata on LCD and no buzzer indication in Normal condition.

Normal conditions:

When temperature < 40C & smoke is absent.

Temperature data will be displayed in transmitter as well as receiver

Abnormal conditions:

Three abnormal conditions can appear

When temperature 40C & smoke is absent,

temperature data will be displayed in receiver side and

buzzer alarm is provided to indicate the rise in

temperature .

When temperature < 40C but smoke is present,


display will be given as SMOKE IS PRESENT along with

the buzzer alarm.

When temperature 40C & smoke is present,


display will be given as SMOKE IS PRESENT along with

the buzzer alarm.


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DATA ACQUISITION 10

2.2 BLOCKDIAGRAM

TRANSMITTER

FIG-2.1 BLOCK DIAGRAM OF TRANSMITTER SECTION

RECEIVER

MICRO

CONTROLLE

R

RS23

2

RF

TRANSRE

CIVER

LCDSmoke

Sensor

Temperatu

re

Sensor

Power

Supply


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DATA ACQUISITION 11

FIG-2.1 BLOCK DIAGRAM OF TRANSMITTER SECTION

FIG 2.1 shows the transmitter section of data

acquisition system and FIG2.2 shows the receiver section of data

acquisition system. Following are the components of these transmitter

and receiver section

2.2.1 POWER SUPPLY

Digital input of 5V is provided for microcontroller and

all other sensor circuitry and 12V is provided for Zigbee module. The

same is followed in both transmitter and receiver section.

2.2.2 TEMPERATURE SENSOR

Temperature sensor converts the temperature into an

equivalent voltage output. IC LM35 is such a sensor. Here we describea simple temperature measurement and display system based on

LM35 sensor and PIC16F877A microcontroller. The temperature in

degrees Celsius is displayed on a 162 LCD.

Continuous monitoring of temperature with 1-second updateinterval (which can be varied in the program)

Temperature measurement using LM35 precision integrated-circuit sensor.

RF

TRANSRECI

VER

RS232

LCD

Power

Supply

BUZZER

MICRO

CONTROLLE

R


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DATA ACQUISITION 12

Precise analogue-to-digital conversion using in-built 10-bitanalogue- to-digital converter (ADC) of PIC16F877Amicrocontroller

2.2.3 SMOKE SENSOR

Here Smoke Sensors that can detect the presence ofcombustible gas and smoke at concentrations from 300 to 10,000ppm. Owing to its simple analog voltage interface, the sensorrequires one analog input pin from the microcontroller. The productcan detect the presence of the smoke and send the output in form ofanalog signals. Our range can function at temperature ranging from-20 to 50C and consume less than 150 mA at 5V.

Two basic types of smoke detectors are used today:ionization and photoelectric. The sensing chambers of these

detectors use different principles of operation to sense the visible orinvisible particles of combustion given off in developing fires.Ionization smoke detector is used here.

2.2.4 MICROCONTROLLER

PIC16F877 is used for computation of sensor data. Thiscontroller consists of 10 bit ADC where it converts analog data in todigital form. This data is compared with a reference temperature andsmoke details. The result will be displayed on LCD and sent to UARTfor RF communication.

In receiver side same PIC16F877 controller is used whereit takes the RS232 signal and decodes. These details will be displayedin LCD.

2.2.5 LCD

Dot matrix LCD of 16 dots per character and two lines is used here. Ithas parallel input of 8 bit. Temperature value is displayed in first line smoke datais displayed n second line. This display is provided both in transmitter andreceiver side.

2.2.6 Buzzer

Rise in temperature data more than 40degree or the presence of smoke

will be indicated by BUZZER.

2.2.7 ZIGBEE module


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DATA ACQUISITION 13

This is the basic part where the data is sent to remote place with thehelp of this module. This is a type of RF communication of frequency more than2.4GHz. Offset QPSK type of modulation is implemented here.

CHAPTER 3 - PERIPHERIALS

3.1 Power supply: The microcontroller and other devices get supply from AC to

DC adaptor through 7805, 5 volt regulator. The adaptor output voltage

level is 12V DC non-regulated. The 7805/7812 voltage regulators are

used to convert 12V to 5V DC. This voltage regulator gives the

regulated output to all peripherals.


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DATA ACQUISITION 14

FIG-3.2. Regulator Schematic

FIG-3.1. 7805 Pin Configuration

3.2 RS232

Standard Details:

In RS-232, user data is sent as a time-series of bits. Both synchronous

and asynchronous transmissions are supported by the standard. In addition to the data

circuits, the standard defines a number of control circuits used to manage the connection

between the DTE and DCE. Each data or control circuit only operates in one direction,

that is, signaling from a DTE to the attached DCE or the reverse. Since transmit data and

receive data are separate circuits, the interface can operate in a full duplex manner,

supporting concurrent data flow in both directions. The standard does not define

character framing within the data stream, or character encoding.

MAX- 232:


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DATA ACQUISITION 15

FIG-3.3 Functional diagram and Logic Diagram of MAX232

Fig-3.3 shows the functional diagram and logical diagram of

MAX232. When a MAX232 IC receives a TTL level to convert, it

changes a TTL Logic 0 to between +3 and +15 V, and changes TTL

Logic 1 to between -3 to -15 V, and vice versa for converting fromRS232 to TTL. This can be confusing when you realize that the RS232

Data Transmission voltages at a certain logic state are opposite from

the RS232 Control Line voltages at the same logic state

Table 3.1 Voltage levels


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DATA ACQUISITION 16

The later MAX232A is backwards compatible with the

original MAX232 but may operate at higher baud rates and can use

smaller external capacitors 0.1 F in place of the 1.0 F capacitors

used with the original device.

The newer MAX3232 is also backwards compatible, butoperates at a broader voltage range, from 3 to 5.5 V.

Pin to pin compatible: ICL232, ST232, ADM232, HIN232

3.3 TEMPERATURE SENSOR LM35

The LM35 is an integrated circuit sensor that can be used to

measure temperature with an electrical output proportional to thetemperature (in C)

In this project, LM35s are used for temperature sensing. Vs

of the LM35s are given 5V and the Vout pins are connected to AN0 of

PIC16F877A (ADC channel).Since the sensor gain (average slope) of

the LM35 is 10mV /C and ADC has 10 bit (210 1000), so pin 5 (Vref)

from PIC16F876A must be given for 1V by using the voltage divider

concept. For preventing the offset, voltage for pin 5 (Vref) should be

adjustable.

3.3.1 Temperature recorder: LM35 pin-out

Temperature recorder: pin-out for the LM35DZ (from the top).

FIG-3.4 Pin out of temperature sensor
http://en.wikipedia.org/wiki/Baudhttp://en.wikipedia.org/wiki/Faradhttp://en.wikipedia.org/wiki/Faradhttp://en.wikipedia.org/wiki/Baudhttp://en.wikipedia.org/wiki/Farad


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DATA ACQUISITION 17

3.3.2 Temperature recorder Circuit

The LM35 is connected to analogue input AN0 which is

also the data input line for programming the 12F675 using ICSP so you

need a way of connecting the sensor and the programming input at

the same time with the programming input overriding the sensor

output (and not damaging the sensor).

This is done here by using 1k resistor that reduces the

current flowing back into the sensor and at the same time is not too

large (so that the ADC can easily convert the sensor output value - the

impedance must be equal to or smaller than 10k Ohm from the

sensor).

The voltage reference for the circuit is taken from pin 6 using

a resistor divider giving a 2.5V reference. This is simply done to

increase the resolution of the ADC as for the LM35 only 0-1V is

generated so you loose ADC range when using a 5V reference. You

could use a lower reference value but this value gives reasonable

results.

Alternatively you could use an amplifier to scale the LM35

output up which would make the ADC less sensitive to noise but for

this project it is simpler not to do so.

Note: The large decoupling capacitor on the supply input of

the 12F675. This reduces noise overall and gives a more consistent

reading. However using a plug block and ADC is not a very good idea

as there is no ground plane and no control over current paths which

you would be able control in a PCB.

In a commercial system the internal ADC is often not used

at all as it is essential to separate the noise introduced to the ADC

using separate grounds and shielding - some designs encase the ADC

in a custom metal shield and along with a ground plane connecting to

the shield gives the best possible result. To overcome noise problems

on the ADC the software averages the input readings so you get a

better result.
http://www.best-microcontroller-projects.com/pic-programming.htmlhttp://www.best-microcontroller-projects.com/pic-programming.html


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DATA ACQUISITION 18

3.4 SMOKE DETECTOR

A smoke detector is a device that detects smoke, typicallyas an indicator of fire. Commercial, industrial, and mass residential

devices issue a signal to a fire alarm system, while household

detectors, known as smoke alarms, generally issue a local audible

and/or visual alarm from the detector itself.

Most smoke detectors work either by optical detection

(photoelectric) or by physical process (ionization), while others use

both detection methods to increase sensitivity to smoke. Sensitive

alarms can be used to detect, and thus deter, smoking in areas where

it is banned such as toilets and schools.

FIG-3.5 Smoke sensor

Ionization method

An ionization type smoke detector is generally cheaper to

manufacture than an optical smoke detector; however, it is sometimes

rejected because it is more prone to false (nuisance) alarms than

photoelectric smoke detectors.

It can detect particles of smoke that are too small to be

visible. It includes about 37 kBq or 1 Ci of radioactive element americium-

241, corresponding to about 0.3 g of the isotope. The radiation passes

through an ionization chamber, an air-filled space between two electrodes,

and permits a small, constant current between the electrodes. Any smoke


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DATA ACQUISITION 19

that enters the chamber absorbs the alpha particles, which reduces the

ionization and interrupts this current, setting off the alarm.

Alpha radiation, as opposed to beta and gamma, is used fortwo additional reasons: Alpha particles have high ionization, sosufficient air particles will be ionized for the current to exist, and theyhave low penetrative power, meaning they will be stopped by theplastic of the smoke detector and/or the air.

Working Principle

Ionization detectors have an ionization chamber and a

source of ionizing radiation. The source of ionizing radiation is a

minute quantity of americium-241 (perhaps 1/5000th of a gram),

which is a source of alpha particles (helium nuclei).The ionization

chamber consists of two plates separated by about a centimeter. The

battery applies a voltage to the plates, charging one plate positive and

the other plate negative.

Alpha particles constantly released by the americium

knock electrons off of the atoms in the air, ionizing the oxygen and

nitrogen atoms in the chamber. The positively-charged oxygen and

nitrogen atoms are attracted to the negative plate and the electrons

are attracted to the positive plate, generating a small, continuous

electric current.

When smoke enters the ionization chamber, the smoke

particles attach to the ions and neutralize them, so they do not reach

the plate. The drop in current between the plates triggers the alarm.

3.5 BUZZER:

FIG-3.5 Buzzer

Features

Resonant Frequency: 4,500Hz

Rated Voltage: 3Vdc (DC input)


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DATA ACQUISITION 20

Operating Voltage: 3 - 18Vdc

Rated Current: 5mA @ 5Vdc

Sound Pressure Level: 70dB @ 3Vdc

Weight: 1 gram

Dimensions: 12mm Diameter, 8.5mm High, Pin Spacing - 7.5mm

3.6 DOT MATRIX LCD:

FIG-3.5 Dot matrix LCD

16 characters x 2 lines

bit parallel lines

RS232 compatible serial interface (2400 & 9600 baud selectable)

Externally selectable serial polarities (Inverted & Non-Inverted)

Serially controllable contrast and backlight levels

user programmable custom characters

16 Byte serial receive buffer

3.7 MICROCONTROLLER:

PIC16F877 is

used for

computation of

the analog

signals from

sensor to

digital form.


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DATA ACQUISITION 21

FIG-3.5 Pin diagram of PIC16F877A

Low-power, high-speed Flash/EEPROM technology

Fully static design

Wide operating voltage range (2.0V to 5.5V)

Commercial and Industrial temperature ranges

Low-power consumption

10-bit, up to 8-channel Analog-to-Digital Converter (A/D)

Analog Comparator module with:

Two analog comparators.

Programmable on-chip voltage reference (VREF) module.

Programmable input multiplexing from device inputs and

internal voltage reference.

Comparator outputs are externally accessible.


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DATA ACQUISITION 22

CHAPTER 4 - RF COMMUNICATION

4.1 .1 CHARECTERISTICS OF ZIGBEE

The focus of network applications under the IEEE 802.15.4 /ZigBee standard include the features of low power consumption,

needed for only two major modes (Tx/Rx or Sleep), high density ofnodes per network, low costs and simple implementation. Thesefeatures are enabled by the following characteristics

2.4GHz and 868/915 MHz dual PHY modes.

This represents three license-free bands: 2.4-2.4835 GHz, 868-

870 MHz and 902-928 MHz. The number of channels allotted to

each frequency band is fixed at 16 channels

In the 2.45 GHz band, 10 channels in the 915 MHz band, and 1

channel in the 868 MHz band

Maximum data rates allowed for each of these frequency bands

are fixed as 250kbps @2.4 GHz, 40 kbps @ 915 MHz, and 20

kbps @868 MHz.

Allocated 16 bit short or 64 bit extended addresses.

Allocation of guaranteed time slots (GTSs)


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DATA ACQUISITION 23

Carrier sense multiple access with collision avoidance (CSMA-CA)

channel access Yields high throughput and low latency for low

duty cycle devices like sensors and controls.

Fully hand-shake acknowledged protocol for transfer reliability.

Low power consumption with battery life ranging from months to

years.

Energy detection (ED).

Link quality indication (LQI).

Multiple topologies : star, peer-to-peer, mesh topologies

4.1.2 NETWORK TOPOLOGIES SUPPROTED BY

ZIGBEE

3 types of topologies that ZigBee supports: startopology, peer-to-peer

topology and cluster tree.

Star Topology

In the star topology, the communication is established

between devices and a single central controller, called the PAN

coordinator. The PAN coordinator may be mains powered while the

devices will most likely be battery powered.

Peer-to-peer Topology

In peer-to-peer topology, there is also one PAN

coordinator. In contrast to star topology, any device can communicate

with any other device as long as they are in range of one another. A

peer-to-peer network can be ad hoc, self-organizing and self-healing. It

also allows multiple hops to route messages from any device to any

other device in the network. It can provide reliability by multipath

routing.


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DATA ACQUISITION 24

Cluster-tree Topology

Cluster-tree network is a special case of a peer-to-peernetwork in which most devices are FFDs and an RFD may connect to a

cluster-tree network as a leave node at the end of a branch. Any of theFFD can act as a coordinator and provide synchronization services toother devices and coordinators. Only one of these coordinatorshowever is the PAN coordinator.

The PAN coordinator forms the first cluster by establishingitself as the cluster head (CLH) with a cluster identifier (CID) of zero,choosing an unused PAN identifier, and broadcasting beacon frames toneighboring devices. A candidate device receiving a beacon framemay request to join the network at the CLH. If the PAN coordinatorpermits the device to join, it will add this new device as a child device

in its neighbor list. The newly joined device will add the CLH as itsparent in its neighbor list and begin transmitting periodic beacons suchthat other candidate devices may then join the network at that device.

Once application or network requirements are met, thePAN coordinator may instruct a device to become the CLH of a newcluster adjacent to the first one. The advantage of this clusteredstructure is the increased coverage area at the cost of increasedmessage latency.

4.1.3 ARCHITECTURE

The LR-WPAN architecture is defined in terms of a numberof blocks in order tosimplify the standard. These blocks are called layers. Each layer isresponsible for onepart of the standard and offers services to the higher layers. Thelayout of the blocks isbased on the open systems interconnection (OSI) seven-layer model.

The interfacesbetween the layers serve to define the logical links between layers.

The LR-WPANarchitecture can be implemented either as embedded devices or asdevices requiring thesupport of an external device such as a PC.

An LR-WPAN device comprises a PHY, which contains theradio frequency (RF) transceiver along with its low-level control

mechanism, and a MAC sub layer that provides access to the physicalchannel for all types of transfer.


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DATA ACQUISITION 25

ARCITECTURE OF ZIGBEE

FIG-4.1 Zigbee architecture

Network and Application Support layer

The network layer permits growth of network sans high

power transmitters. This layer can handle huge numbers of nodes.This level in the ZigBee architecture includes The ZigBee Device Object (ZDO) User-Defined Application Profile(s) The Application Support (APS) Sub-layer.

The APS sub-layer's responsibilities include maintenance oftables that enable matching between two devices and communicationamong them, and also discovery, the aspect that identifies otherdevices that operate in the operating space of any device.

The responsibility of determining the nature of the device (Coordinator

/ FFD or RFD) in


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DATA ACQUISITION 26

the network, commencing and replying to binding requests andensuring a secure relationship between devices rests with the ZDO(Zigbee Define Object). The user-definedapplication refers to the end device that conforms to the ZigBeeStandard.

4.1.4 Traffic Types

ZigBee/IEEE 802.15.4 addresses three typical traffic types.IEEE 802.15.4 MAC can accommodate all the types.

Data is periodic. The application dictates the rate, and thesensor activates checks for data and deactivates.

Data is intermittent. The application, or other stimulus,determines the rate, as in the case of say smoke detectors. Thedevice needs to connect to the network only when

communication is necessitated. This type enables optimumsaving on energy.

Data is repetitive, and the rate is fixed a priori. Depending onallotted time slots, called GTS (guaranteed time slot), devicesoperate for fixed durations

ZigBee employs either of two modes, beacon or non-beacon to enable the to-and-fro data traffic. Beacon mode is usedwhen the coordinator runs on batteries and thus offers maximumpower savings, whereas the non-beacon mode finds favour when thecoordinator is mains-powered.

4.1.5 Block diagram of RF (ZIGBEE) TRANSCEIVER

IEEE 802.15.4 Modulation Format:This section is meant as an introduction to the 2.4 GHz

direct sequence spread

spe6ctrum (DSSS) RF modulation format defined in IEEE 802.15.4.

The modulation and spreading functions are illustrated at

block level in Figure below. Each byte is divided into two symbols, 4bits each. The least significant symbol is transmitted first. For multi-


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DATA ACQUISITION 27

byte fields, the least significant byte is transmitted first, except for

security related fields where the most significant byte it transmitted

first. Each symbol is mapped to one out of 16 pseudo-random

sequences, 32 chips each. The symbol to chip mapping is shown in

Table 3. The chip sequence is then transmitted at 2 MChips/s, with the

least significant chip (C0) transmitted first for each symbol.

FIG-4.2 Zigbee Transmitter

Channel filtering and frequency offset compensation is

performed digitally. The signal level in the channel is estimated to

generate the RSSI level. Data filtering is also included for enhanced

performance. With the 40 ppm frequency accuracy requirement from

[1], a compliant receiver must be able to compensate for up to 80 ppm

or 200 kHz. The CC2420demodulator tolerates up to 300 kHz offset

without significant degradation of the receiver performance.

Soft decision is used at the chip level, i.e. the demodulator

does not make a decision for each chip, only for each received symbol.

De-spreading is performed using

over sampled symbol co-relaters. Symbol synchronization is achieved

by a continuous start of frame delimiter (SFD) search. When a SFD is

detected, data is written to the RXFIFO and may be read out by the

microcontroller at a lower bit rate than the 250 kbps generated by the

receiver. The demodulator also handles symbol rate errors in excess of

120 ppm without performance degradation.

4.2. TYPE OF MODULATION

4.2.1 QPSK

QPSK uses four points on the constellation diagram,

equispaced around a circle. With four phases, QPSK can encode two

bits per symbol


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DATA ACQUISITION 28

FIG-5.1 Constellation diagram of QPSK

The mathematical analysis shows that QPSK can be usedeither to double the data rate compared with a BPSK system whilemaintaining the samebandwidth of the signal, or to maintain the data-rate of BPSKbut halving the bandwidth needed. In this latter case, theBER of QPSK is exactly the same as the BER of BPSK - and decidingdifferently is a common confusion when considering or describingQPSK.

The advantage of QPSK over BPSK becomes evident: QPSK

transmits twice the data rate in a given bandwidth compared to BPSK -

at the same BER. The engineering penalty that is paid is that QPSK

transmitters and receivers are more complicated than the ones for

BPSK. However, with modern electronics technology, the penalty in

cost is very moderate.

QPSK signal in the time domain

The modulated signal is shown below for a short segment of a

random binary data-stream. The two carrier waves are a cosine wave

and a sine wave, as indicated by the signal-space analysis above.Here, the odd-numbered bits have been assigned to the in-phase

component and the even-numbered bits to the quadrature component

(taking the first bit as number 1). The total signal the sum of the

two components is shown at the bottom. Jumps in phase can be

seen as the PSK changes the phase on each component at the start of

each bit-period. The topmost waveform alone matches the description

given for BPSK above.
http://en.wikipedia.org/wiki/Bandwidth_(signal_processing)http://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Bandwidth_(signal_processing)http://en.wikipedia.org/wiki/Electronics


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DATA ACQUISITION 29

d

FIG-5.2 QPSK waveform

4.2.2 OQPSK - Offset quadrature

phase-shift keying

Offset quadrature phase-shift keying (OQPSK) is a variant ofphase-shift keying modulation using 4different values of the phase totransmit. It is sometimes called

staggered quadrature phase-shiftkeying (SQPSK).


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DATA ACQUISITION 30

FIG-5.3 Constellation diagram of OQPSK

Taking four values of the phase (two bits) at a time toconstruct a QPSK symbol can allow the phase of the signal to jump byas much as 180 at a time. When the signal is low-pass filtered (as istypical in a transmitter), these phase-shifts result in large Amplitudefluctuations, an undesirable quality in communication systems. Byoffsetting the timing of the odd and even bits by one bit-period, or halfa symbol-period, the in-phase and quadrature components will never

change at the same time. In the constellation diagram shown on theright, it can be seen that this will limit the phase-shift to no more than90 at a time. This yields much lower amplitude fluctuations than non-offset QPSK and is sometimes preferred in practice.

The picture on the right shows the difference in the behaviorof the phase between ordinary QPSK and OQPSK. It can be seen that inthe first plot the phase can change by 180 at once, while in OQPSKthe changes are never greater than 90.

The modulated signal is shown below for a short segment of a

random binary data-stream. Note the half symbol-period offsetbetween the two component waves. The sudden phase-shifts occurabout twice as often as for QPSK (since the signals no longer changetogether), but they are less severe. In other words, the magnitude of

jumps is smaller in OQPSK when compared to QPSK.
http://en.wikipedia.org/wiki/Bithttp://en.wikipedia.org/wiki/Bit


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DATA ACQUISITION 31

FIG-5.4 OQPSK waveform

4.2.3 QPSK SIGNAL VERSUS OQPSK


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DATA ACQUISITION 32

FIG-5.5 QPSK waveform vs OQPSK waveform


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DATA ACQUISITION 33

.

CHAPTER 5 HARDWARE IMPLEMENTATION

5.1 SENSOR AND TRANSMITTER SECTION


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DATA ACQUISITION 34

FIG-5.1 RF transmitter

Fig-6.1 shows the basic schematic of project data

acquisition using RF(zigbee) Transmitter. These two inputs are taken

where the temperature data and smoke details are sensing.

Microcontroller PIC16F877 is used to take the following input andconvert in to RS232 form and send the data in to Zigbee module. This

data is sent wia wireless communication to remote places. The same

data is displayed on LCD also. Individual module Schematic is as

shown in below Fig.

5.1.1 SMOKE SENSOR SCHEMATIC


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DATA ACQUISITION 35

FIG-5.2 Smoke sensor and driver circuit .

5.1.2 Temperature sensor

FIG-5.3 Temperature sensor and driver circuit .


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DATA ACQUISITION 36

5.2 RF RECEIVER


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DATA ACQUISITION 37

FIG-5.4 Temperature sensor and driver circuit .

Fig5.4 shows the basic schematic of project Data

acquisition using RF(zigbee) Receiver. On the receiver side same

Zigbee transceiver module collects the RF data. This data is convertedin to RS232 form by MAX232 converter. The data from MAX232 is giver

to PIC16F877 receiver. This data is collected or monitored in remote

places where it is displayed in LCD and buzzer indication is provided if

temperature is more than 40o. Buzzer indication is also provided if

there is a presence of smoke.

CHAPTER 6 - FIRMWARE LOGIC

6.1 FLOWCHART AND FIRMWARE LOGIC

START

Configure all ports

and Registers as per

the requirement

Display Weathermonitoring

using ZIGBEE

If output of

Smoke sensor

is high OR

Temperature

value is more

than 40degree

STOP

Read the

Temperature value

& smoke sensor

status from I/O pin

Display

Temperature value

and Smoke status

as normal

Display Temperature value

and Smoke status as normal

Turn ON the Buzzer

NO

YES


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DATA ACQUISITION 38

Above flow chart shows the software flow of DATAACQUISITION USING RF COMMUNICATION All the ports should be

initialized as output port because it should not pick any other noise.

The required port which is used for input should be made as input.

Microcontroller PIC16F877 consists of 10bit ADC where it

receives analog signal and converts in to digital form as shown in block

diagram Fig-6.1

FIG-6.1 ADC from PIC controller and displayed on LCD.

The temperature data and smoke details are taken as input

from I/O pin. Now the reference is fixed as it compares with 40degree

of temperature value and 200 relative humidity of smoke value. If

these value varies beyond the limit then Buzzer indication is provided

at receiver section. Indication provided on LCD both at transmitter and

receiver section.

IC PIC16F877A is an 8-bit microcontrollerwith 8k14-bit flash

program memory, 368 bytes of RAM and many other extra peripherals

like ADC, universal synchronous asynchronous receiver transmitter,

master synchronous serial port, timers, compare capture and pulse-

width modulation modules, and analogue comparators. It is based on

the reduced instruction set computer (RISC) architecture.


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DATA ACQUISITION 39

The microcontroller processes the sensor output to compute

the temperature in degree Celsius. The internal ADC of the

microcontroller is used to convert the analogue output of the sensor

into its equivalent digital value. The internal ADC of the microcontroller

has eight channels of analogue input and gives 10-bit digital output. In

this project, the r e f e r e n c e voltage to the ADC is the same as thesupply voltage to the microcontroller,i.e, 5V.

The resolution of the ADC can be calculated as follows: (as it is a 10-bit

ADC)

= 5/1023

= 4.887 mV

It means that for 4.887mV change in the analogue input, the ADC

output changes by binary 1 with a reference voltage of 5V. Analogue

output of the sensor at its pin 2 is connected to Port A at RA0 forconversion into digital equivalent. The control lines EN, R/W and RS of

the LCD module are connected to microcontroller pins 18.19 & 20,

respectively. The commands and the data to be displayed are sent to

the LCD module in the nibble mode from microcontroller.

CHAPTER 7 - SOFTWARE

7.1 MPLAB IDE v8.60

MPLAB IDE is a Windows Operating System (OS) software

program that runs on a PC to develop applications for Microchip

microcontrollers and digital signal controllers. It is called an Integrated

Development Environment, or IDE, because it provides a single

integrated "environment" to develop code for embedded

microcontrollers.

Embedded systems

An embedded system is typically a design making use ofthe power of a small microcontroller, like the Microchip PIC MCU or

dsPIC Digital Signal Controller (DSCs). These microcontrollers combinea microprocessor unit (like the CPU in a desktop PC) with someadditional circuits called "peripherals", plus some additional circuits onthe same chip to make a small control module requiring few otherexternal devices. This single device can then be embedded into otherelectronic and mechanical devices for low-cost digital control.

MPLAB Editor

The MPLAB Editor is an integrated part of the MPLAB IDE

Integrated Development Environment. The editor is always availablewhen MPLAB IDE is running.


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DATA ACQUISITION 40

The MPLAB IDE and MPLAB Editor are designed to providedevelopers with an easy and quick method to develop and debugfirmware for Microchip Technology's PIC microcontroller (MCU) andDSPIC digital signal controller (DSC) product families.

MPLINK Linker

MPLINK object linker (the linker) combines object modulesgenerated by the MPASM assembler or the MPLAB C18 C compiler intoa single executable (hex) file. The linker also accepts libraries of objectfiles as input, as geneated by the MPLIB object librarian. The linkingprocess is controlled by a linker script file, which is also input intoMPLINK linker.

MPLAB ICD 2 debugger

The MPLAB ICD 2 is a low-cost in-circuit debugger (ICD) andin-circuit serial programmer (ICSP). MPLAB ICD 2 is intended to beused as an evaluation, debugging and programming aid in a laboratoryenvironment.

The MPLAB ICD 2 offers these features:

Real-time and single-step code execution

Breakpoints, Register and Variable Watch/Modify

In-circuit debugging

Target Vdd monitor

Diagnostic LEDs

MPLAB IDE user interface

RS-232 serial or USB interface to a host PC

7.2 STEPS IN DEVELOPING A PROGRAM

Setting Up the Environment


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DATA ACQUISITION 41

Running the Project Wizard

Viewing the Project

Creating a HEX File

Setting Debug Options

Setting Up the Demo Board

Loading Program Code For Debugging Running TUT452

Debugging TUT452

Programming the ApplicationTUT452

Main Routine and Source Code

CHAPTER 8 - ADVANTAGES & APPLICATIONSAND LIMITATIONS

8.1 ADVANTAGES

1. Better accuracy.

2. Avoiding human error.

3. Increases speed and saves time.

4. Cost effective.

8.2 APPLICATIONS:

The major applications of data acquisition using RF communication

(ZIGBEE) is

Manufacturing industries where the continuous data needed to

be monitored data communication is required for different

modules in industrial campus.


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DATA ACQUISITION 42

In hospitals it has advantage to gather the information.

Remote temperature alarm for poultry sheds:

Wireless Temperature Monitoring and alarm can be used to

remotely monitor incubator temperature, egg storage room

temperature, broiler sheds, water level and humidity. Optional

outputs can also be used to control ventilation fans and heating

devices

Industrial and commercial remote wireless temperature

monitoring system.

Home and industrial automation systems

8.3 LIMITATIONS:

Range of communication reduced when there is obstacles

between transmitter and receiver.

Since no security data may be received by unintended receiver.

CHAPTER 9 - DEVELOPMENT AND RESULTS

9.1 DEVELOPMENT STEPS

The development of project is done in various stages.

a. Stage 1: Study of all the components carried in this stage.

RF communication

Various modulation techniques

Sensors

Embedded codingDetailed study is done on the above factors


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DATA ACQUISITION 43

b. Stage 2: Circuit diagram is prepared and verified in Multisim

software.

c. Stage 3: Circuit connection is done first on breadboard.

d. Stage 4: Since it is wireless communication the range of

communication is checked

and noted.e. Stage 5: Coding is done in MPLAB software.

f. Stage 6: Report preparation is done.

The prototype of Data acquisition using RF was designed as discussed

in previous chapters.

9.2. RESULT

The input dc 12V is given to the power supply circuit. The power ON

LED indication is provided to each of the modules. This power on

indication is mainly implemented for debug purpose. In transmitter

side as soon as circuit powers ON it senses the temperature & Smoke

data and displays on LCD. Refer Tablexx for detailed transmitter and

receiver LCD display output.

On the receiver side, the input dc 12V is given to the power supply

circuit. The power ON LED indication is provided to each of the

modules. This power on indication is mainly implemented for debug

purpose. If any data is collected by receiver from transmitter then itshows the corresponding value on LCD. If no data is received by

receiver it waits for the data by displaying weather monitoring using

ZIGBEE.

Table.9.1 Display pattern for different conditions of input

Condition TRANSMITTER RECEIVER

Temperature is within

40 degree Celsius and

absent of smoke


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DATA ACQUISITION 44

Temperature value is

more than 40 degree

Celsius and smoke is

present

When receiver is not receiving data from transmitter then the display

will be shown as below FIG 8.1

FIG-9.1 Display pattern when no transmitter input .

10. CONCLUSION:

The fundamental aim of this project is to design a

wireless weather system which enables to monitor the weather

parameter in an industry by using zigbee technology and display the


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DATA ACQUISITION 45

parameter on the PCs screen using visual basic. The components

used in the circuit are readily available. The individual sub-circuits

have been designed on PCB and tested for functioning in the

laboratory. The test has been performed by placing the sensor board

both in an indoor and outdoor and the parameters are noted and

checked with the analog transducers for errors and the errors will bevery less. ZigBee targets applications not addressable by Bluetooth

or any other wireless standard.

The Zigbee based wireless weather station is essentially

a design and implementation project of wireless technology. To

approach a project like this a parallel path has to be taken in regards

to the theory and the practical circuitry, for a successful conclusion in

any project the paths must meet, and this only happens when they

are fully understood. This is why a good grounding in the basics ofDigital, Computer interfacing ports & programming in micro controller

,visual basic6.0 language must be achieved before ever approaching

a project like this. To start off looking at basic of wireless device was

must. This is what made the overall project challenging and

rewarding.

The design use for this project is essentially quite a

simple one, and it is this simplicity which partly brings it down when

it comes to the overall reliable performance.

11. FUTURE SCOPE OF ZIGBEE:

The zigbee technology can be wide used for home and

industrial automation. It lead to the cheap wireless technology, so

that it can be widely used for low rate data transfer. It can also be

used for the remote control unit like toys, etc. We got a proposed

zigbee universal remote controller. It requires only 200us of latency

and high efficient use of power. Zigbee is the best for where the

battery is replaced very rarely.

12. REFERENCES

www.zigbeealliance.com

www.wikipedia.org

Wireless Communication System by Roody Coolen

Communication Electronics by Freznel


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DATA ACQUISITION 46

DATASHEE

T

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