25.Wireless Data Communication

INDEX

1. INTRODUCTION

2. MICROCONTROLLER

2.1 A Brief History of 8051

2.2 Description of 89C52 Microcontroller

2.3 Block Diagram of Microcontroller

2.4 Pin Configurations

2.5 Timers

2.6 Interrupts

2.7 Special function registers:

2.8 Memory Organization

3. POWER SUPPLY

3.1 Description

3.2 Block Diagram

3.3 Circuit Diagram

3.4 IC Voltage Regulators

4. ULN 2003

4.1 Pin Connection

4.2 Description

5. LCD

5.2 Description

5.1 Pin Connection

6.1 Description RF Receiver Module - RX433

6.2 RF Transmitter Module-TX433

7. KEIL SOFTWARE

8.1 Software Description

9. CIRCUIT DIAGRAM

10.SOURCE CODING

11.CONCLUSION

FUTURE SCOPE

BIBLIOGRAPHY

REFERENCES

Wireless Data Transfer using RF Communication

ABSTRACT

In Today’s Electronic communication take important role. Using

Today’s Communication technology the data transmission and reception from one

Place to another is easy and fast.

In our project we have two sections, one is transmitter another one

Receiver, in transmitting section we have AT89C52 Microcontroller, PC and

LCD. In receiver section we have another AT89C52Microcontroller and LCD

At the time when data will transfer from the transmitter a predefined code will be

Added with every eight bit data and when this data receive by the receiver this code

Will be decode by the receiver and generate the exact data that will be displayed

On LCD.

In this project Wireless Encoding and decoding are using one of the techniques

Called cipher text technique. Encryption is any procedure to convert plaintext into

Cipher text. Decryption is any procedure to convert cipher text into plaintext.

Hardware components:

AT 89C52 Micro controllers LCD RF Module. MAX 232 DB-9 Connector.

Software tools:

Kiel vision.

Advantages:

The data secure is more while transferring data Used in data communication.

Applications:

This system can be used for Military application for security.

It can be used in Air craft applications.

BLOCK DIAGRAM

TRANSMITTER RECEIVER

EMBEDDED CONTROLLER

LCD

RegulatedPower Supply

RF Receiver module

EMBEDDED CONTROLLER

MAX232

RegulatedPower supply

RF Transmitter

module

PC

2. MICROCONTROLLER

2.1 A Brief History of 8051

In 1981, Intel Corporation introduced an 8 bit microcontroller

called 8051. This microcontroller had 128 bytes of RAM, 4K bytes of chip

ROM, two timers, one serial port, and four ports all on a single chip. At

the time it was also referred as “A SYSTEM ON A CHIP”

The 8051 is an 8-bit processor meaning that the CPU can work

only on 8 bits data at a time. Data larger than 8 bits has to be broken

into 8 bits pieces to be processed by the CPU. The 8051 has a total of

four I\O ports each 8 bit wide.

There are many versions of 8051 with different speeds and

amount of on-chip ROM and they are all compatible with the original

8051. This means that if you write a program for one it will run on any of

them.

The 8051 is an original member of the 8051 family. There are two

other members in the 8051 family of microcontrollers. They are 8052

and 8031. All the three microcontrollers will have the same internal

architecture, but they differ in the following aspects.

8031 has 128 bytes of RAM, two timers and 6

interrupts.

89C51 has 4KB ROM, 128 bytes of RAM, two

timers and 6 interrupts.

89C52 has 8KB ROM, 128 bytes of RAM, three

timers and 8 interrupts.

Of the three microcontrollers, 89C51 is the most preferable.

Microcontroller supports both serial and parallel communication.

In the concerned project 89C52 microcontroller is used. Here

microcontroller used is AT89C52, which is manufactured by ATMEL

laboratories.

2.2 Description of 89C52 Microcontroller

The AT89C52 provides the following standard features: 8Kbytes of

Flash, 256 bytes of RAM, 32 I/O lines, three 16-bit timer/counters, six-

vector two-level interrupt architecture, a full duplex serial port, on-chip

oscillator, and clock circuitry. In addition, the AT89C52 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.

By combining a versatile 8-bit CPU with Flash on a monolithic chip,

the AT89C52 is a powerful microcomputer which provides a highly

flexible and cost effective solution to many embedded control

applications.

Features of Microcontroller (89C52)

Compatible with MCS-51 Products

8 Kbytes of In-System Reprogrammable Flash Memory

Endurance: 1,000 Write/Erase Cycles

Fully Static Operation: 0 Hz to 24 MHz

Three-Level Program Memory Lock

256 x 8-Bit Internal RAM

32 Programmable I/O Lines

Three 16-Bit Timer/Counters

Eight vector two level Interrupt Sources

Programmable Serial Channel

Low Power Idle and Power Down Modes

In addition, the AT89C52 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.

2.3 Block Diagram of Microcontroller

Figure 2.1 Block Diagram Of 89C52

2.4 Pin Configurations

Figure 2.2 Pin Diagram of 89C52

Pin Description

VCC

Pin 40 provides Supply voltage to the chip. The voltage source is +5v

GND.

Pin 20 is the grounded

Port 0

Port 0 is an 8-bit open drain bidirectional I/O port from pin 32 to

39. 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.

Port 1

Port 1 is an 8-bit bidirectional I/O port with internal pull-ups from

pin 1 to 8. 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.

In addition, P1.0 and P1.1 can be configured to be the

timer/counter 2 external count input (P1.0/T2) and the timer/counter 2

trigger input (P1.1/T2EX), respectively, as shown in following table.

Port 1 also receives the low-order address bytes during Flash

programming and program verification.

Port 2


pin 21 to 28. 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.

Port 3


pin 10 to 17. 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 (IIL) because

of the pull-ups.

Port 3 also serves the functions of various special features of the

AT89C52 as listed below:

Table 2.1 Special Features of port3

Port 3 also receives some control signals for Flash programming

and programming verification.

RST

Pin 9 is the Reset input. It is active high. Upon applying a high

pulse to this pin, the microcontroller will reset and terminate all

activities. A high on this pin for two machine cycles while the oscillator is

running resets the device.

ALE/PROG

Address Latch is an output pin and is active high. Address 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.

PSEN

Program Store Enable is the read strobe to external program

memory. When the AT89C52 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.

EA/VPP

External 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 when 12-volt programming is selected.

XTAL1

Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

XTAL2

Output from the inverting oscillator amplifier.

Oscillator Characteristics

XTAL1 and XTAL2 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 5.3. 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 5.4.

Figure 2.3 crystal connections

Figure 2.4 External Clock Drive Configuration

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.

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 a hardware reset. It should be noted that when idle is terminated by a hardware 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.

Power down Mode

In 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.

Table 2.2 Status Of External Pins During Idle and Power

Down Mode

Program Memory Lock Bits

On the chip are three lock bits which can be left unprogrammed

(U) or can be programmed (P) to obtain the additional features listed in

the table 5.4. 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.

Table 2.3 Lock Bit Protection Modes

TIMERS

Timer 0 and 1

Timer 0 and Timer 1 in the AT89C52 operate the same way as

Timer 0 and Timer 1 in the AT89C51.

Register pairs (TH0, TL1), (TH1, TL1) are the 16-bit counter

registers for timer/counters 0 and 1.

Timer 2

Timer 2 is a 16-bit Timer/Counter that can operate as either a

timer or an event counter. The type of operation is selected by bit C/T2

in the SFR T2CON. Timer 2 has three operating modes: capture, auto-

reload (up or down counting), and baud rate generator. The modes are

selected by bits in T2CON, as shown in Table 5.2. Timer 2 consists of two

8-bit registers, TH2 and TL2. In the Timer function, the TL2 register is

incremented every machine cycle. Since a machine cycle consists of 12

oscillator periods, the count rate is 1/12 of the oscillator frequency.

Table 2.4 Timer 2 Operating Modes

In the Counter function, the register is incremented in response to

a 1-to-0 transition at its corresponding external input pin, T2. In this

function, the external input is sampled during S5P2 of every machine

cycle. When the samples show a high in one cycle and a low in the next

cycle, the count is incremented. The new count value appears in the

register during S3P1 of the cycle following the one in which the

transition was detected. Since two machine cycles (24 oscillator periods)

are required to recognize a 1-to-0 transition, the maximum count rate is

1/24 of the oscillator frequency. To ensure that a given level is sampled

at least once before it changes, the level should be held for at least one

full machine cycle.

There are no restrictions on the duty cycle of external input

signal, but it should for at least one full machine to ensure that a given

level is sampled at least once before it changes.

Capture Mode

In the capture mode, two options are selected by bit EXEN2 in

T2CON. If EXEN2 = 0, Timer 2 is a 16-bit timer or counter which upon

overflow sets bit TF2 in T2CON.This bit can then be used to generate an

interrupt. IfEXEN2 = 1, Timer 2 performs the same operation, but a 1-to-

0 transition at external input T2EX also causes the current value in TH2

and TL2 to be captured into RCAP2H andRCAP2L, respectively. In

addition, the transition at T2EXcauses bit EXF2 in T2CON to be set. The

EXF2 bit, likeTF2, can generate an interrupt.

Auto-reload (Up or Down Counter)

Timer 2 can be programmed to count up or down when configured

in its 16-bit auto-reload mode. This feature is invoked by the DCEN

(Down Counter Enable) bit located in the SFR T2MOD (see Table 4). Upon

reset, the DCEN bit is set to 0 so that timer 2 will default to count up.

When DCEN is set, Timer 2 can count up or down, depending on the

value of the T2EX pin. Table2.5: T2MOD-Timer 2 Mode Control Register

Table2.6: T2CON-Timer/Counter2 Control Register

2.5 Interrupts

The AT89C52 has a total of six interrupt vectors: two external

interrupts (INT0 and INT1), three timer interrupts (Timers 0, 1, and 2),

and the serial port interrupt. These interrupts are all shown in Figure 2.5

Figure 2.5 Interrupts source

Each of these interrupt sources can be individually enabled or

disabled by setting or clearing a bit in Special Function Register IE. IE

also contains a global disable bit, EA, which disables all interrupts at

once.

Note that Table 5.3 shows that bit position IE.6 is unimplemented.

In the AT89C51, bit position IE.5 is also unimplemented. User software

should not write 1s to these bit positions, since they may be used in

future AT89 products.

Table 2.7 Interrupts Enable Register

Timer 2 interrupt is generated by the logical OR of bits TF2 and

EXF2 in register T2CON. Neither of these flags is cleared by hardware

when the service routine is vectored to. In fact, the service routine may

have to determine whether it was TF2 or EXF2 that generated the

interrupt, and that bit will have to be cleared in software.

The Timer 0 and Timer 1 flags, TF0 and TF1, are set at S5P2 of the

cycle in which the timers overflow. The values are then polled by the

circuitry in the next cycle. However, the Timer 2 flag, TF2, is set at S2P2

and is polled in the same cycle in which the timer overflows.

2.6 Special function registers:

Special function registers are the areas of memory that control

specific functionality of the 89c52 microcontroller.

a) Accumulator (0E0h)

As its name suggests, it is used to accumulate the results of large

no. of instructions. It can hold 8 bit values.

b) B register (oFoh)

The B register is very similar to accumulator. It may hold 8-bit

value. The B register is only used by MUL AB and DIV AB instructions. In

MUL AB the higher byte of the products gets stored in B register. In DIV

AB the quotient gets stored in B with the remainder in A.

c) Stack pointer (081h)

The stack pointer holds 8-bit value. This is used to indicate where

the next value to be removed from the stack should be taken from.

When a value is to be pushed on to the stack, the 8052 first store the

value of SP and then store the value at the resulting memory location.

When a value is to be popped from the stack, the 8052 returns the value

from the memory location indicated by SP and then decrements the

value of SP.

d) Data pointer (Data pointer low/high, address 82/83h)

The SFRs DPL and DPH work together to represent a 16-bit value

called the data pointer. The data pointer is used in operations regarding

external RAM and some instructions code memory. It is a 16-bit SFR and

also an addressable SFR.

e) Program counter

The program counter is a 16 bit register, which contains the 2

byte address, which tells the next instruction to execute to be found in

memory. When the 8052 is initialized PC starts at 0000h and is

incremented each time an instruction is executes. It is not addressable

SFR.

f) PCON (power control, 87h)

The power control SFR is used to control the 8052’s power control

modes. Certain operation modes of the 8052 allow the 8052 to go into a

type of “sleep mode” which consumes low power.

g)TCON(Timer control, 88h)

The timer mode control SFR is used to configure and modify the

way in which the 8052’s two timers operate. This SFR controls whether

each of the two timers is running or stopped and contains a flag to

indicate that each timer has overflowed. Additionally, some non-timer

related bits are located in TCON SER. These bits are used to configure

the way in which the external interrupt flags are activated, which are set

when an external interrupt occur.

h)TMOD(Timer Mode,89h)

The timer mode SFR is used to configure the mode of operation of

each of the two timers. Using this SR your program may configure each

timer to be a 16-bit timer, or 13 bit timer, 8-bit auto reload timer, or two

separate timers. Additionally you may configure the timers to only count

when an external pin is activated or to count “events” that are indicated

on an external pin.

TIMER1 TIMER0

i) T0 (Timer 0 low/ high, address 8A/ 8C h)

SMOD ---- --- ---- GF1 GF0

PD IDL

TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0

Gate

C/ T M1 M0 Gate

C/ T M1 M0

These two SFRs together represent timer 0. Their exact behavior

depends on how the timer is configured in the TMOD SFR; however,

these timers always count up. What is configurable is how and when

they increment value.

j) T1 (Timer 1 low/ high, address 8B/ 8D h)

These two SFRs together represent timer 1. Their exact behavior

depends on how the timer is configured in the TMOD SFR; however,

these timers always count up. What is configurable is how and when

they increment in value.

k) P0 (Port 0, address 80h, bit addressable)

This is port 0 latch. Each bit of this SFR corresponds to one of the

pins on a micro controller. Any data to be outputted to port 0 is first

written on P0 register. For e.g., bit 0 of port 0 is pin P0.0, bit 7 is pin

P0.7. Writing a value of 1 to a bit of this SFR will send a high level on the

corresponding I/O pin whereas a value of 0 will bring it to low level.

l) P1(Port 1, address 90h, bit addressable)






m) P2 (Port 2, address 0A0h, bit addressable)






n) P3 (Port 3, address 0B0h, bit addressable)






o) IE (Interrupt Enable, 0A8h)

The interrupt enable SFR is used to enable and disable specific interrupts. The low

7 bits of the SFR are used to enable/disable the specific interrupts, where the MSB bit is

used to enable or disable all the interrupts. Thus, if the high bit of IE 0 all interrupts are

disabled regardless of whether an individual interrupt is enabled by setting a lower bit.

EA _ _ _

ET2 ES ET1 EX1 ET0 EX0

p) IP (Interrupt Priority, 0B8h)

The interrupt priority SFR is used to specify the relative priority of each interrupt.

On 8052, an interrupt may be either low or high priority. An interrupt may interrupt

interrupts. For e.g., if we configure all interrupts as low priority other than serial interrupt.

The serial interrupt always interrupts the system; even if another interrupt is currently

executing no other interrupt will be able to interrupt the serial interrupt routine since the

serial interrupt routine has the highest priority.

_ _ _ _ _ _ PT2 PS PT1 PX1 PT0 PX0

q)PSW (Program Status Word, 0D0h)

The Program Status Word is used to store a number of important

bits that are set and cleared by 8052 instructions. The PSW SFR contains

the carry flag, the auxiliary carry flag, the parity flag and the overflow

flag. Additionally, it also contains the register bank select flags, which

are used to select, which of the “R” register banks currently in use.

r) SBUF (Serial Buffer, 99h)

SBUF is used to hold data in serial communication. It is physically

two registers. One is writing only and is used to hold data to be

transmitted out of 8052 via TXD. The other is read only and holds

received data from external sources via RXD. Both mutually exclusive

registers use address 99h.S

2.7 Memory Organization

The total memory of 89C52 system is logically divided in Program

memory and Data memory. Program memory stores the programs to be

executed, while data memory stores the data like intermediate results,

variables and constants required for the execution of the program.

Program memory is invariably implemented using EPROM, because it

stores only program code which is to be executed and thus it need not

be written into. However, the data memory may be read from or written

to and thus it is implemented using RAM.

Further, the program memory and data memory both may be

categorized as on-chip (internal) and external memory, depending upon

whether the memory physically exists on the chip or it is externally

interfaced. The 89C52 can address 8Kbytes on-chip memory whose map

starts from 0000H and ends at 1FFFH. It can address 64Kbytes of

external program memory under the control of PSEN (low) signal.

The AT89C52 implements 256 bytes of on-chip RAM. The upper

128 bytes occupy a parallel address space to the Special Function

Registers. That means the upper 128bytes have the same addresses as

the SFR space but are physically separate from SFR space. When an

instruction accesses an internal location above address 7FH, the address

mode used in the instruction specifies whether the CPU accesses the

CY AC F0 RS1 RS0 OV - - - - P

upper 128 bytes of RAM or the SFR space. Instructions that use direct

addressing access SFR space. For example, the following direct

addressing instruction accesses the SFR at location 0A0H (which is P2).

MOV 0A0H, #data

Instructions that use indirect addressing access the upper128

bytes of RAM. For example, the following indirect addressing instruction,

where R0 contains 0A0H, accesses the data byte at address 0A0H,

rather than P2 (whose address is 0A0H)

.MOV @R0, #data

Note that stack operations are examples of indirect addressing, so the

upper 128 bytes of data RAM are available as stack space.

7. REGULATED POWER SUPPLY

7.1 Description:

A variable regulated power supply, also called a

variable bench power supply, is one where you can continuously

adjust the output voltage to your requirements. Varying the output

of the power supply is the recommended way to test a project

after having double checked parts placement against circuit

drawings and the parts placement guide. This type of regulation is

ideal for having a simple variable bench power supply. Actually

this is quite important because one of the first projects a hobbyist

should undertake is the construction of a variable regulated power

supply. While a dedicated supply is quite handy e.g. 5V or 12V, it's

much handier to have a variable supply on hand, especially for

testing. Most digital logic circuits and processors need a 5 volt

power supply. To use these parts we need to build a regulated 5

volt source. Usually you start with an unregulated power supply

ranging from 9 volts to 24 volts DC (A 12 volt power supply is

included with the Beginner Kit and the Microcontroller Beginner

Kit.). To make a 5 volt power supply, we use a LM7805 voltage

regulator IC .

http://www.iguanalabs.com/mbkit.htm

http://www.iguanalabs.com/mbkit.htm

http://www.iguanalabs.com/1stled.htm

The LM7805 is simple to use. You simply connect the

positive lead of your unregulated DC power supply (anything from

9VDC to 24VDC) to the Input pin, connect the negative lead to the

Common pin and then when you turn on the power, you get a 5

volt supply from the Output pin.

Circuit Features:

Brief description of operation: Gives out well regulated +5V

output, output current capability of 100 mA

Circuit protection: Built-in overheating protection shuts

down output when regulator IC gets too hot

Circuit complexity: Very simple and easy to build

Circuit performance: Very stable +5V output voltage,

reliable operation

Availability of components: Easy to get, uses only very

common basic components

Design testing: Based on datasheet example circuit, I have

used this circuit successfully as part of many electronics projects

Applications: Part of electronics devices, small laboratory

power supply

Power supply voltage: Unregulated DC 8-18V power supply

Power supply current: Needed output current + 5 mA

Component costs: Few dollars for the electronics

components + the input transformer cost

7.2 Block Diagram:

7.3 Circuit Diagram:

Basic Power Supply Circuit:

Above is the circuit of a basic unregulated dc power supply. A

bridge rectifier D1 to D4 rectifies the ac from the transformer secondary,

which may also be a block rectifier such as WO4 or even four individual

diodes such as 1N4004 types. (See later re rectifier ratings).

The principal advantage of a bridge rectifier is you do not need a

centre tap on the secondary of the transformer. A further but significant

advantage is that the ripple frequency at the output is twice the line

frequency (i.e. 50 Hz or 60 Hz) and makes filtering somewhat easier.

As a design example consider we wanted a small unregulated

bench supply for our projects. Here we will go for a voltage of about 12 -

13V at a maximum output current (IL) of 500ma (0.5A). Maximum ripple

will be 2.5% and load regulation is 5%.

Now the RMS secondary voltage (primary is whatever is consistent

with your area) for our power transformer T1 must be our desired output

Vo PLUS the voltage drops across D2 and D4 (2 * 0.7V) divided by 1.414.

This means that Vsec = [13V + 1.4V] / 1.414 which equals about 10.2V.

Depending on the VA rating of your transformer, the secondary voltage

will vary considerably in accordance with the applied load. The

secondary voltage on a transformer advertised as say 20VA will be much

greater if the secondary is only lightly loaded.

If we accept the 2.5% ripple as adequate for our purposes then at

13V this becomes 13 * 0.025 = 0.325 Vrms. The peak to peak value is

2.828 times this value. Vrip = 0.325V X 2.828 = 0.92 V and this value is

required to calculate the value of C1. Also required for this calculation is

the time interval for charging pulses. If you are on a 60Hz system it it 1/

(2 * 60) = 0.008333 which is 8.33 milliseconds. For a 50Hz system it is

0.01 sec or 10 milliseconds.

Remember the tolerance of the type of capacitor used here is

very loose. The important thing to be aware of is the voltage rating

should be at least 13V X 1.414 or 18.33. Here you would use at least the

standard 25V or higher (absolutely not 16V).With our rectifier diodes or

bridge they should have a PIV rating of 2.828 times the Vsec or at least

29V. Don't search for this rating because it doesn't exist. Use the next

highest standard or even higher. The current rating should be at least

twice the load current maximum i.e. 2 X 0.5A or 1A. A good type to use

would be 1N4004, 1N4006 or 1N4008 types.

These are rated 1 Amp at 400PIV, 600PIV and 1000PIV

respectively. Always be on the lookout for the higher voltage ones when

they are on special.

7.4 IC Voltage Regulators:

Voltage regulators comprise a class of widely used ICs.

Regulator IC units contain the circuitry for reference source,

comparator amplifier, control device, and overload protection all in

a single IC. Although the internal construction of the IC is

somewhat different from that described for discrete voltage

regulator circuits, the external operation is much the same. IC

units provide regulation of either a fixed positive voltage, a fixed

negative voltage, or an adjustably set voltage.

A power supply can be built using a transformer connected to the

ac supply line to step the ac voltage to desired amplitude, then

rectifying that ac voltage, filtering with a capacitor and RC filter, if

desired, and finally regulating the dc voltage using an IC regulator. The

regulators can be selected for operation with load currents from

hundreds of mill amperes to tens of amperes, corresponding to power

ratings from mill watts to tens of watts.

Three-Terminal Voltage Regulators:

Fixed Positive Voltage Regulators:

Vin

Vout

C1 C2

Fig shows the basic connection of a three-terminal voltage

regulator IC to a load. The fixed voltage regulator has an

unregulated dc input voltage, Vi, applied to one input terminal, a

regulated output dc voltage, Vo, from a second terminal, with the

third terminal connected to ground. While the input voltage may

vary over some permissible voltage range, and the output load

may vary over some acceptable range, the output voltage remains

constant within specified voltage variation limits. A table of

positive voltage regulated ICs is provided in table. For a selected

regulator, IC device specifications list a voltage range over which

the input voltage can vary to maintain a regulated output voltage

IN OUT

78XX

GND

over a range of load current. The specifications also list the

amount of output voltage change resulting from a change in load

current (load regulation) or in input voltage (line regulation).

TABLE: Positive Voltage Regulators in 7800 series

IC No. Output voltage(v) Maximum input voltage(v)

7805

7806

7808

7810

7812

7815

7818

7824

+5

+6

+8

+10

+12

+15

+18

+24

35V

40V

RF Receiver Module - RX433Remote Control Products

RF Receiver Module RX433

Click these images for a larger view.

This compact radio frequency (RF) receiver module is suitable for remote control or

telemetry applications. The double sided circuit board is pre-populated with Surface

Mount Devices (SMD) and is tuned to 433MHz. No module assembly or

adjustments are required. RF receiver module RX433 receives RF control signals

from the 8 channel RF remote control transmitter K8058 and performs as an RF

receiver interface when used on the 8 channel remote control relay board K8056.

(Only one RX433 RF receiver is needed for full RF remote control operation of the

8 channel relay board K8056). RF receiver module RX433 is a highly sensitive

passive design that is easy to implement with a low external parts count. (Download

datasheet with hook-up schematic below)

RF remote receiver module RX433 can also be used with 433MHz RF Transmitter

TX433N for your custom remote control or telemetry requirements. (However, the

http://www.apogeekits.com/relay_board_remote_control_k8056.htm

http://www.apogeekits.com/8_channel_rf_remote_control.htm

http://www.apogeekits.com/images/rf_receiver_module_rx433.jpg

http://www.apogeekits.com/images/rf_receiver_module_433mhz.jpg

FCC has restrictions on the sale of the TX433N transmitter module in the U.S., so

we don't have these transmitters available).

RF Receiver Module Features

no RF receiver module adjustments required

stable output

suitable for RF remote controls, telemetry, ...

Specifications

RF receiver frequency: 433MHz

receiver range: 220 yards (200m) in open air

modulation: AM

modulate mode: ASK

circuit shape: LC

sensitivity: 3µVrms

power supply: 4.5 - 5.5V DC

data rate: 4800 bps

receiver selectivity: -106 dB

channel spacing: 1 MHz

digital and linear output

RF receiver module pin numbers

o 1: gnd

o 2: digital output

o 3: linear output

o 4: Vcc

o 5: Vcc

o 6: gnd

o 7: gnd

o 8: antenna: 11.8" - 13.77" (30cm - 35cm)

TX433: 433MHz Transmitter Module

VIEW LARGER

IMAGE

Modulation : AM

RF output : 8mW

Power supply : 3 - 12Vdc

Power Supply and All Input /

Output Pins: -0.3 to +12.0 V

*Non-Operating Case Temperature: -20 to +85

*Soldering Temperature ( 10 Seconds ) : 230 ( 10 Seconds )

Features

no adjustments required

stable output

suitable for remote controls, telemetry, ..Specifications

frequency : 433MHz

modulation : AM

RF output : 8mW

power supply : 3 - 12Vdc

http://store.qkits.com/images/TX433.jpg



Circuit Shape: SAW

Data Rate: 8 kbps

pin numbers :

1 : GND

2 : Data_IN

3 : Vcc

4 : ANTLCD:- To send any of the commands from given

table to the lcd, make pin RS =0.For data, make RS=1.then send a

high to low pulse to the E pin to enable the internal latch of the

LCD. As shown in figure for LCD connections.

Pin number

Symbol Level I/O Function

1 Vss - - Power supply (GND)

2 Vcc - - Power supply (+5V)

3 Vee - - Contrast adjust

4 RS 0/1 I0 = Instruction input1 = Data input

Pin number


5 R/W 0/1 I0 = Write to LCD module1 = Read from LCD module

6 E 1, 1->0 I Enable signal

7 DB0 0/1 I/O Data bus line 0 (LSB)

8 DB1 0/1 I/O Data bus line 1






14 DB7 0/1 I/O Data bus line 7 (MSB)

Table 2.2., Pin assignment for > 80 character displays

Pin number


1 DB7 0/1 I/O Data bus line 7 (MSB)





Pin number





8 DB0 0/1 I/O Data bus line 0 (LSB)

9 E1 1, 1->0 IEnable signal row 0 & 1 (1stcontroller)

10 R/W 0/1 I0 = Write to LCD module1 = Read from LCD module

11 RS 0/1 I0 = Instruction input1 = Data input

12 Vee - - Contrast adjust

13 Vss - - Power supply (GND)

14 Vcc - - Power supply (+5V)

15 E2 1, 1->0 IEnable signal row 2 & 3 (2ndcontroller)

16 n.c.

Table 2.4. Bit names

Bit name

Setting / Status

I/D 0 = Decrement cursor position1 = Increment cursor position

S 0 = No display shift 1 = Display shift


Pin number


D 0 = Display off 1 = Display on

C 0 = Cursor off 1 = Cursor on

B 0 = Cursor blink off1 = Cursor blink on

S/C 0 = Move cursor 1 = Shift display

R/L 0 = Shift left 1 = Shift right

DL 0 = 4-bit interface 1 = 8-bit interface

N 0 = 1/8 or 1/11 Duty (1 line)1 = 1/16 Duty (2 lines)

F 0 = 5x7 dots 1 = 5x10 dots

BF 0 = Can accept instruction1 = Internal operation in progress

KEIL SOFTWARESOFTWARE DESCRIPTION:Click on the Keil uVision Icon on Desktop

1. The following fig will appear

2. Click on the Project menu from the title bar

3. Then Click on New Project

4. Save the Project by typing suitable project name with no extension in u r own

folder sited in either C:\ or D:\

5. Then Click on Save button above.

6. Select the component for u r project. i.e. Atmel……

7. Click on the + Symbol beside of Atmel

8. Select AT89C51 as shown below

9. Then Click on “OK”

10. The Following fig will appear

11. Then Click either YES or NO………mostly “NO”

12. Now your project is ready to USE

13. Now double click on the Target1, you would get another option “Source group

1” as shown in next page.

14. Click on the file option from menu bar and select “new”

15. The next screen will be as shown in next page, and just maximize it by double

clicking on its blue boarder.

16. Now start writing program in either in “C” or “ASM”

17. 99For a program written in Assembly, then save it with extension “. asm” and

for “C” based program save it with extension “ .C”

18. Now right click on Source group 1 and click on “Add files to Group

Source”

19. Now you will get another window, on which by default “C” files will

appear.

20. Now select as per your file extension given while saving the file

21. Click only one time on option “ADD”

22. Now Press function key F7 to compile. Any error will appear if so

happen.

23. If the file contains no error, then press Control+F5 simultaneously.

24. The new window is as follows

25. Then Click “OK”

26. Now Click on the Peripherals from menu bar, and check your required

port as shown in fig below

27. Drag the port a side and click in the program file.

28. Now keep Pressing function key “F11” slowly and observe.

You are running your program successfully

CONCLUSION

Embedded systems are emerging as a technology with high potential. In the past

decades micro processor based embedded system ruled the market. The last decade

witnessed the revolution of Microcontroller based embedded systems. This project

basically deals with how many number of persons are in the room very accurately with the

help of Microcontroller. With regards to the requirements gathered the manual work and

the complexity in counting can be achieved with the help of electronic devices.

FUTURE SCOPE

This system is a rapidly growing field and there are new and improved

strategies popping up all the time. For the most part these systems are all built around the

same basic structure, a central box that monitors several detectors and perimeter guards

and sounds an alarm when any of them are triggered.

This system is best for guiding the perimeter of a house or a business center

the points where an intruder would enter the building. In this system IR sensor is used to

detect the intrusion. Similarly the vibration and temperature sensors recognize vibration

disturbances and accidental fires respectively.

This project provides an efficient and economical security system. This

system finds applications in industries, banks and homes.

Incorporating the features discussed below can further enhance the system

This system can detect intrusion only at discrete points. This system

detection feature can be extended to scanning a complete area. Thus the

intrusion into the building can be detected with much more efficiently.

The redialing feature can also be incorporated such that if the call is not put

forward the first time, the auto dialer will dial the same number until the call

is successfully completed.

A pre-recorded voice message can delivered to the owner notifying him about

the intrusion into the premises.

The addition of the above discussed advancements certainly builds this

project into a much flexible and reliable security system.

REFERENCES

1. The 8051 Microcontroller and Embedded Systems By Muhammad Ali Mazidi

2. Fundamentals Of Embedded Software By Daniel W Lewis

3..www.howsstuffworks.com

4. www.alldatasheets.com

5. www.electronicsforu.com

6. www.knowledgebase.com

7.www.8051 projectsinfo.com

8.Datasheets of Microcontroller AT89C52

9. Datasheets of 555 timer

10. Datasheets of TSAL 6200

11. Datasheets of TSOP 1356

12. Datasheets of BC 547

http://www.knowledgebase.com/

http://www.electronicsforu.com/

http://WWW.howsstuffworks.com/

25.Wireless Data Communication

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