b.naresh-9494406519 Sri Sai College of Eng & Technology (2)

8/2/2019 b.naresh-9494406519 Sri Sai College of Eng & Technology (2)

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WIRELESS ELECTRONIC NOTICE BOARD

CHAPTER.1.

1.INTRODUCTION

1.1 DESCRIPTION OF THE PROJECT:

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 PC and zigBee module. In receiver section we have

ZigBee, AT89S52Microcontroller 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.

Whatever the commands sent on the transmitter side in the hyper terminal it will

be passed to receiver section through zigBee which will act like wireless transmitter and

the respective command will received by the another zigBee module which will act

like a wireless receiver in this case and the commands will read by the microcontroller

and act according to the commands the respective functionality is seen on the LCD

display which will be connected to the microcontroller.

DEPT OF ECE 1 SSCET




1.2 BLOCK DIAGRAM:

TRANSMITTER

RECEIVER

DEPT OF ECE 2 SSCET




1.3 EMBEDDED SYSTEMS:

Embedded systems are designed to do some specific task, rather than be a

general-purpose computer for multiple tasks. Some also have real time performance

constraints that must be met, for reason such as safety and usability; others may have

low or no performance requirements, allowing the system hardware to be simplified to

reduce costs.

An embedded system is not always a separate block - very often it is physically

built-in to the device it is controlling. The software written for embedded systems is

often called firmware, and is stored in read-only memory or flash convector chips rather

than a disk drive. It often runs with limited computer hardware resources: small or nokeyboard, screen, and little memory.

Wireless communication has become an important feature for commercial

products and a popular research topic within the last ten years. There are now more

mobile phone subscriptions than wired-line subscriptions. Lately, one area of

commercial interest has been low-cost, low-power, and short-distance wireless

communication used for personal wireless networks." Technology advancements are

providing smaller and more cost effective devices for integrating computational

processing, wireless communication, and a host of other functionalities. These

embedded communications devices will be integrated into applications ranging from

homeland security to industry automation and monitoring. They will also enable custom

tailored engineering solutions, creating a revolutionary way of disseminating and

processing information. With new technologies and devices come new business

activities, and the need for employees in these technological areas. Engineers who have

knowledge of embedded systems and wireless communications will be in high demand.

Unfortunately, there are few adorable environments available for development and

classroom use, so students often do not learn about these technologies during hands-on

lab exercises. The communication mediums were twisted pair, optical fiber, infrared,

and generally wireless radio.

DEPT OF ECE 3 SSCET




CHAPTER.2.

2.HARDWARE FEATURES

2.1. Power Supply.

2.2 AT89S52 Microcontroller.

2.3 ZigBee.

2.4 LCD.

2.5.Max 232.

2.1 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 to obtain a pure constant DC voltage.

50HZ

Fig2.1.: Circuit Diagram

a)Transformer:

Usually, DC voltages are required to operate various electronic equipment and

these voltages are 5V, 9V or 12V. But these voltages cannot be obtained directly. Thus

DEPT OF ECE 4 SSCET

230V AC

50HZ

Bridge

Rectifier

step down

transformer

Filter Regulator

D.C

Output




the A.C input available at the mains supply i.e., 230V is to be brought down to the

required voltage level. This is done by a transformer. Thus, a step down transformer is

employed to decrease the voltage to a required level.

b)Rectifier:

The output from the transformer is fed to the rectifier. It converts A.C. into

pulsating D.C. The rectifier may be a half wave or a full wave rectifier. In this project, a

bridge rectifier is used because of its merits like good stability and full wave

rectification.

c)Filter:

Capacitive filter is used in this project. It removes the ripples from the output of

rectifier and smoothens the D.C. Output received from this filter is constant until the

mains voltage and load is maintained constant. However, if either of the two is varied,

D.C. voltage received at this point changes. Therefore a regulator is applied at the

output stage.

d)Voltage Regulator:

As the name itself implies, it regulates the input applied to it. A voltage

regulator is an electrical regulator designed to automatically maintain a constant voltage

level. In this project, power supply of 5V and 12V are required. In order to obtain these

voltage levels, 7805 and 7812 voltage regulators are to be used. The first number 78

represents positive supply and the numbers 05, 12 represent the required output voltage

levels. 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.

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

DEPT OF ECE 5 SSCET




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 (Integrated Circuit). The IC

is shown below.

Fig.2.1.(a): LM7805 IC

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.

DEPT OF ECE 6 SSCET

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

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

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

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




BLOCK DIAGRAM:

Fig2.1.(b): Components of a typical linear power supply

This 5V DC acts as Vcc to the microcontroller. The excess voltage is dissipated

as heat via an Aluminum heat sink attached to the voltage regulator. For both positive

and negative swings of the transformer, there is a Forward path through the diode

bridge. Both conduction paths cause Current to flow in the same direction through the

load resistor, accomplishing full-wave rectification. While one set of diodes is forward

biased, the other set is reverse biased and effectively eliminated from the circuit.

DEPT OF ECE 7 SSCET




e)Bridge Rectifier:

Fig2.1(c): Power Supply Circuit Diagram

A diode bridge is an arrangement of four diodes connected in a bridge circuit as

shown below, that provides the same polarity of output voltage for any polarity of the

input voltage. When used in its most common application, for conversion of alternating

current (AC) input into direct current (DC) output, it is known as a bridge rectifier. The

diagram describes a diode-bridge design known as a full-wave rectifier. This design can

be used to rectify single phase AC when no transformer center tap is available. A

bridge rectifier makes use of four diodes in a bridge arrangement to achieve full-wave

rectification. This is a widely used configuration, both with individual diodes wired as

shown and with single component bridges where the diode bridge is wired internally.

2.1.1.CIRCUIT FEATURES:

a)Brief description of operation:

Gives out well regulated +5V output, output current capability of 100 mA.

b)Circuit protection:

Built-in overheating protection shuts down output when regulator IC gets too hot.

c)Circuit complexity:

DEPT OF ECE 8 SSCET




Very simple and easy to build

d)Circuit performance:

Very stable +5V output voltage, reliable operation.

e)Availability of components:

Easy to get, uses only very common basic components.

f)Design testing:

Based on datasheet example circuit, I have used this circuit successfully as part of many

electronics projects

2.1.2Applications:

Part of electronics devices, small laboratory power supply

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

b)Power supply current: Needed output current + 5 mA

2.2.AT89C51

a) 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”

b)AT89S52:

DEPT OF ECE 9 SSCET




The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller

with 8K bytes of in-system programmable Flash memory. The device is manufactured

using Atmel’s high-density nonvolatile memory technology and is compatible with the

industry-standard 80C51 instruction set and pinout. The on-chip Flash allows the

program memory to be reprogrammed in-system or by a conventional nonvolatile

memory pro-grammer. By combining a versatile 8-bit CPU with in-system

programmable Flash on a monolithic chip, the Atmel AT89S52 is a powerful

microcontroller, which provides a highly flexible and cost-effective solution to many,

embedded control applications. The AT89S52 provides the following standard features:

8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers,

three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex

serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 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 con-tents but freezes the oscillator, disabling all other chip

functions until the next interrupt.

DEPT OF ECE 10 SSCET




Fig. 2.2:AT89C51 Microcontroller

8031128 bytes of RAM, two timers and 6 interrupts.

8051 4K ROM, 128 bytes of RAM, two timers and 6 interrupts.

8052 has 8K ROM, 256 bytes of RAM, three timers and 8 interrupts.Of the three microcontrollers, 8051 is the most preferable. Microcontroller

supports both serial and parallel communication.

In the concerned project 8052 microcontroller is used. Here microcontroller

used is AT89S52, which is manufactured by ATMEL laboratories.

The 8051 is the name of a big family of microcontrollers. The device which we are

going to use along this tutorial is the 'AT89S52' which is a typical 8051 microcontroller

manufactured by Atmel™. Note that this part doesn't aim to explain the functioning of

the different components of a 89S52 microcontroller, but rather to give you a general





idea of the organization of the chip and the available features.

The block diagram provided by Atmel™ in their datasheet howing the architecture the

89S52 device can seem very complicated, and since we are going to use the C high

level language to program it, a simpler architecture can be represented as the figure

This figures shows the main features and components that the designer can

interact with. You can notice that the 89S52 has 4 different ports, each one having 8

Input/output lines providing a total of 32 I/O lines. Those ports can be used to output

DATA and orders do other devices, or to read the state of a sensor, or a switch. Most of

the ports of the 89S52 have 'dual function' meaning that they can be used for two

different functions: the fist one is to perform input/output operations and the second one

is used to implement special features of the microcontroller like counting external

pulses, interrupting the execution of the program according to external events,

performing serial data transfer or connecting the chip to a computer to update the

software.

c)Necessity of Microcontrollers:

Microprocessors brought the concept of programmable devices and made many

applications of intelligent equipment. Most applications, which do not need large

amount of data and program memory, tended to be costly.

The microprocessor system had to satisfy the data and program requirements so,

sufficient RAM and ROM are used to satisfy most applications .The peripheral control

equipment also had to be satisfied. Therefore, almost all-peripheral chips were used in

the design. Because of these additional peripherals cost will be comparatively high.

d)8085 chip needs:

An Address latch for separating address from multiplex address and data.32-

KB RAM and 32-KB ROM to be able to satisfy most applications. As also Timer /

Counter, Parallel programmable port, Serial port, and Interrupt controller are needed for

its efficient applications.

In comparison a typical Micro controller 8051 chip has all that the 8051 board

has except a reduced memory as follows.

4K bytes of ROM as compared to 32-KB, 128 Bytes of RAM as compared to 32-KB.





e)Bulky:

On comparing a board full of chips (Microprocessors) with one chip with all

components in it (Microcontroller).

f)Debugging:

Lots of Microprocessor circuitry and program to debug. In Micro controller

there is no Microprocessor circuitry to debug.

Slower Development time: As we have observed Microprocessors need a lot of

debugging at board level and at program level, where as, Micro controller do not have

the excessive circuitry and the built-in peripheral chips are easier to program for

operation.

So peripheral devices like Timer/Counter, Parallel programmable port, Serial

Communication Port, Interrupt controller and so on, which were most often used were

integrated with the Microprocessor to present the Micro controller .RAM and ROM

also were integrated in the same chip. The ROM size was anything from 256 bytes to

32Kb or more. RAM was optimized to minimum of 64 bytes to 256 bytes or more.

Microprocessor has following instructions to perform:

1. Reading instructions or data from program memory ROM.

2. Interpreting the instruction and executing it.

3. Microprocessor Program is a collection of instructions stored in a Nonvolatile

memory.

4. Read Data from I/O device

5. Process the input read, as per the instructions read in program memory.

6. Read or write data to Data memory.

7. Write data to I/O device and output the result of processing to O/P device.

2.2.1.Introduction to AT89S52:





The system requirements and control specifications clearly rule out the use of

16, 32 or 64 bit micro controllers or microprocessors. Systems using these may be

earlier to implement due to large number of internal features. They are also faster and

more reliable but, the above application is satisfactorily served by 8-bit micro

controller. Using an inexpensive 8-bit Microcontroller will doom the 32-bit product

failure in any competitive market place. Coming to the question of why to use 89S52 of

all the 8-bit Microcontroller available in the market the main answer would be because

it has 8kB Flash and 256 bytes of data RAM32 I/O lines, three 16-bit timer/counters, a

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

and clock circuitry.

In addition, the AT89S52 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.

The Flash program memory supports both parallel programming and in Serial In-

System Programming (ISP). The 89S52 is also In-Application Programmable (IAP),

allowing the Flash program memory to be reconfigured even while the application is

running.

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

AT89S52 is a powerful microcomputer which provides a highly flexible and cost

effective solution to many embedded control applications.

2.2.2.Features:

Compatible with MCS-51 Products

8K Bytes of In-System Reprogrammable Flash Memory

Fully Static Operation: 0 Hz to 33 MHz

Three-level Program Memory Lock

256 x 8-bit Internal RAM

32 Programmable I/O Lines

Three 16-bit Timer/Counters

Eight Interrupt Sources





Programmable Serial Channel

Low-power Idle and Power-down Modes

4.0V to 5.5V Operating Range

Full Duplex UART Serial Channel

Interrupt Recovery from Power-down Mode

Watchdog Timer

Dual Data Pointer

Power-off Flag

Fast Programming Time

Flexible ISP Programming (Byte and Page Mode)

2.2.3.PIN DIAGRAM:

FIG-2.2.3. PIN DIAGRAM OF 89S52 IC

2.2.3.1Pin Description:





a)VCC: Supply voltage.

b)GND: Ground.

c)Port 0:

Port 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

highimpedance inputs.Port 0 can also be configured to be the multiplexed loworder

address/data bus during accesses to external program and data memory. In this mode,

P0 has internal pullups. 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.

d)Port 1:

Port 1 is an 8-bit bidirectional I/O port with internal pullups. 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 pullups 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 pullups.

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 the following table. Port 1 also receives the low-order address bytes during

Flash programming and verification.

Table2.2.3.: Port1 Configuration

e)Port 2:





Port 2 is an 8-bit bidirectional I/O port with internal pullups.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

pullups. Port 2 emits the high-order address byte during fetches from external program

memory and during accesses to external data memory that use 16-bit addresses (MOVX

@ DPTR). In this application, Port 2 uses strong internal pull-ups when emitting 1s.

During accesses to external data memory that use 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.

f)Port 3:

Port 3 is an 8-bit bidirectional I/O port with internal pullups.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 pullups and can be used as inputs. As inputs, Port 3 pins that

are externally being pulled low will source current (IIL) because of the pullups. Port 3

also serves the functions of various special features of the AT89S52, as shown in the

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

verification.

Table.2.2.3.(a): Port3 Configuration

g)RST:





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

running resets the device. This pin drives High for 96 oscillator periods after the

Watchdog times out. The DISRTO bit in SFR AUXR (address 8EH) can be used to

disable this feature. In the default state of bit DISRTO, the RESET HIGH out feature is

enabled. ALE/PROG Address Latch Enable (ALE) is an 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.

h)PSEN:

Program Store Enable (PSEN) is the read strobe to external program memory.

When the AT89S52 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.

i)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.

j)XTAL1:







the microcontroller. The manufacturers make 8051 designs that run at specific

minimum and maximum frequencies typically 1 to 16 MHz.

Fig2.2.4: Oscillator and timing circuit

2.2.5.MEMORIES:

2.2.5.1.Types of memory:

The 8052 have three general types of memory. They are on-chip memory,

external Code memory and external Ram. On-Chip memory refers to physically

existing memory on the micro controller itself. External code memory is the code

memory that resides off chip. This is often in the form of an external EPROM. External

RAM is the Ram that resides off chip. This often is in the form of standard static RAM

or flash RAM.





a) Code memory:

Code memory is the memory that holds the actual 8052 programs that is to be

run. This memory is limited to 64K. Code memory may be found on-chip or off-chip. It

is possible to have 8K of code memory on-chip and 60K off chip memory

simultaneously. If only off-chip memory is available then there can be 64K of off chip

ROM. This is controlled by pin provided as EA.

b) Internal RAM:

The 8052 have a bank of 256 bytes of internal RAM. The internal RAM is

found on-chip. So it is the fastest Ram available. And also it is most flexible in terms of

reading and writing. Internal Ram is volatile, so when 8051 is reset, this memory is

cleared. 256 bytes of internal memory are subdivided. The first 32 bytes are divided

into 4 register banks. Each bank contains 8 registers. Internal RAM also contains 256

bits, which are addressed from 20h to 2Fh. These bits are bit addressed i.e. each

individual bit of a byte can be addressed by the user. They are numbered 00h to FFh.

The user may make use of these variables with commands such as SETB and CLR.

2.2.5.2.Special Function registered memory:

Special function registers are the areas of memory that control specific

functionality of the 8052 micro controller.

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 registers (0F0h):





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 product gets stored in B register. In div AB the quotient gets stored in B

with the remainder in A.

C)Sack pointer (81h):

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 onto 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:

The SFRs DPL and DPH work together 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 8052 where 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):







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

These two SFRs taken 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 in value.

j) T1 (Timer 1 Low/High, address 8B/ 8D h):

These two SFRs, taken together, represent timer 1. Their exact behavior

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

always count up.

k) P0 (Port 0, address 90h, 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):

This is port latch1. Each bit of this SFR corresponds to one of the pins on a


e.g., bit 0 of port 0 is pin P1.0, bit 7 is pin P1.7. Writing a value of 1 to a bit of this SFR


low level.

m) P2 (port 2, address 0A0h, bit addressable):

This is a port latch2. Each bit of this SFR corresponds to one of the pins on a


e.g., bit 0 of port 0 is pin P2.0, bit 7 is pin P2.7. Writing a value of 1 to a bit of this SFR






low level.

n) P3 (port 3, address B0h, bit addressable):

This is a port latch3. Each bit of this SFR corresponds to one of the pins on a


e.g., bit 0 of port 0 is pin P3.0, bit 7 is pin P3 .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.

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 is 0 all

interrupts are disabled regardless of whether an individual interrupt is enabled by

setting a lower bit.

Table.2.2.5.2.(c):IE Register.

p) IP (Interrupt Priority, 0B8h):

The interrupt priority SFR is used to specify the relative priority of eachinterrupt. On 8051, an interrupt maybe 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. However, if a serial interrupt is executing no other

interrupt will be able to interrupt the serial interrupt routine since the serial interrupt

routine has the highest priority.





Table.2.2.5.2.(d):IP Register.

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.

Table.2.2.5.2(e):PSW Register.

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.

2.3 ZIGBEE

2.3.1.Introduction:

When we hold the TV remote and wish to use it we have to necessarily point

our control at the device. This one-way, line-of-sight, short-range communication uses

infrared (IR) sensors to enable communication and control and it is possible to operate

the TV remotely only with its control unit.

Add other home theatre modules, an air- conditioner and remotely enabled fans

and lights to your room, and you become a juggler who has to handle not only these





remotes, but also more numbers that will accompany other home appliances you are

likely to use.

Some remotes do serve to control more than one device after ‘memorizing'

access codes, but this interoperability is restricted to LOS, that too only for a set of

related equipment, like the different units of a home entertainment system

Now picture a home with entertainment units, security systems including fire alarm,

smoke detector and burglar alarm, air-conditioners and kitchen appliances all within

whispering distance from each other and imagine a single unit that talks with all the

devices, no longer depending on line-of-sight, and traffic no longer being one-way.

This means that the devices and the control unit would all need a common standard to

enable intelligible communication. ZigBee is such a standard for embedded application

software and has been ratified in late 2004 under IEEE 802.15.4 Wireless Networking

Standards.

ZigBee is an established set of specifications for wireless personal area

networking (WPAN), i.e., digital radio connections between computers and related

devices. This kind of network eliminates use of physical data buses like USB and

Ethernet cables. The devices could include telephones, hand-held digital assistants,

sensors and controls located within a few meters of each other.

ZigBee is one of the global standards of communication protocol formulated by

the relevant task force under the IEEE 802.15 working group. The fourth in the series,

WPAN Low Rate/ZigBee is the newest and provides specifications for devices that

have low data rates, consume very low power and are thus characterized by long battery

life. Other standards like Bluetooth and IrDA address high data rate applications such

as voice, video and LAN communications.

The ZigBee Alliance has been set up as “an association of companies working

together to enable reliable, cost-effective, low-power, wirelessly networked, monitoring

and control products based on an open global standard”.

Once a manufacturer enrolls in this Alliance for a fee, he can have access to the

standard and implement it in his products in the form of ZigBee chipsets that would be

built into the end devices. Philips, Motorola, Intel, HP are all members of the Alliance .

The goal is “to provide the consumer with ultimate flexibility, mobility, and ease of use

by building wireless intelligence and capabilities into every day devices. ZigBee

technology will be embedded in a wide range of products and applications across

consumer, commercial, industrial and government markets worldwide. For the first


http://www.tutorial-reports.com/wireless/bluetooth

http://www.zigbee.org/




http://www.tutorial-reports.com/wireless/bluetooth








time, companies will have a standards-based wireless platform optimized for the unique

needs of remote monitoring and control applications, including simplicity, reliability,

low-cost and low-power”.

The target networks encompass a wide range of devices with low data rates in

the Industrial, Scientific and Medical (ISM) radio bands, with building-automation

controls like intruder/fire alarms, thermostats and remote (wireless) switches,

video/audio remote controls likely to be the most popular applications. So far sensor

and control devices have been marketed as proprietary items for want of a standard.

With acceptance and implementation of ZigBee, interoperability will be enabled in

multi-purpose, self-organizing mesh networks





Fig. 2.3.1: ZigBee Module.

2.3.2.ZigBee Characteristics:

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 of nodes per network, low costs and simple

implementation.





These features are enabled by the following characteristics (technical data from

ZigBee: 'Wireless Control That Simply Works') 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

sixteen (numbered 11-26), one (numbered 0) and ten (numbered 1-10) respectively. The

higher frequency band is applicable worldwide, and the lower band in the areas of

North America, Europe, Australia and New Zealand .

Low power consumption, with battery life ranging from months to years.

Considering the number of devices with remotes in use at present, it is easy to see that

more numbers of batteries need to be provisioned every so often, entailing regular (as

well as timely), recurring expenditure. In the ZigBee standard, longer battery life is

achievable by either of two means: continuous network connection and slow but sure

battery drain, or intermittent connection and even slower battery drain.

• Maximum data rates allowed for each of these frequency bands are fixed as 250

kbps @2.4 GHz, 40 kbps @ 915 MHz, and 20 kbps @868 MHz.

• High throughput and low latency for low duty-cycle applications (<0.1%)

• Channel access using Carrier Sense Multiple Access with Collision Avoidance

(CSMA - CA)

• Addressing space of up to 64 bit IEEE address devices, 65,535 networks

• 50m typical range

• Fully reliable “hand-shake” data transfer protocol.

• Different topologies as illustrated below: star, peer-to-peer, mesh

Fig2.3.2: ZigBee Topologies.


http://www.zigbee.org/en/resources/






2.3.3.Technology Comparisons:

The Why “ZigBee” question has always had an implied, but never quite worded

follower phrase “…when there is Bluetooth”. A comparative study of the two can befound in ZigBee: 'Wireless Control That Simply Works' .

The bandwidth of Bluetooth is 1 Mbps, ZigBee's is one-fourth of this value. The

strength of Bluetooth lies in its ability to allow interoperability and replacement of

cables, ZigBee's, of course, is low costs and long battery life.

In terms of protocol stack size, ZigBee's 32 KB is about one-third of the stack

size necessary in other wireless technologies (for limited capability end devices, the

stack size is as low as 4 KB).

Most important in any meaningful comparison are the diverse application areas

of all the different wireless technologies. Bluetooth is meant for such target areas as

wireless USB's, handsets and headsets, whereas ZigBee is meant to cater to the sensors

and remote controls market and other battery operated products.

In a gist, it may be said that they are neither complementary standards nor

competitors, but just essential standards for different targeted applications. The earlier

Bluetooth targets interfaces between PDA and other device (mobile phone / printer etc)

and cordless audio applications.

The IEEE 802.15.4–based ZigBee is designed for remote controls and sensors,

which are very many in number, but need only small data packets and, mainly,

extremely low power consumption for (long) life. Therefore they are naturally different

in their approach to their respective application arenas.

2.3.4.RF Trans-receiver:

This is an FSK Transceiver module, which is designed using the

ChipconIC(CC2500). It is a true single-chip transceiver, It is based on 3 wire digital

serial interface and an entire Phase-Locked Loop (PLL) for precise local oscillator

generation .so the frequency could be setting. It can use in UART / NRZ / Manchester

encoding / decoding. It is a high performance and low cost module. It gives 30 meters

range with onboard antenna. In a typical system, this trans-receiver will be used

together with a microcontroller. It provides extensive hardware support for packet









handling, data buffering, burst transmissions ,clear channel assessment, link quality

indication and wake on radio . It can be used in 2400-2483.5 MHz ISM/SRD band

systems. (eg. RKE-two way Remote Keyless Entry, wireless alarm and security

systems, AMR-automatic Meter Reading, Consumer Electronics, Industrial monitoring

and control, Wireless Game Controllers, Wireless Audio/Keyboard/Mouse). It could

easily to design product requiring wireless connectivity. It can be used on wireless

security system or specific remote-control function and others wireless

system.Operating Range is 30 meters without requiring any external antenna.

2.3.5.Features:

• Low power consumption.

• Integrated bit synchronizer.

• Integrated IF and data filters.

• High sensitivity (type -104dBm)

• Programmable output power -20dBm~1dBm

• Operation temperature range : -40~+85 deg C

• Operation voltage: 1.8~3.6 Volts.

• Available frequency at : 2.4~2.483 GHz

• Digital RSSI

• Automation system.





2.3.6.Pin Diagram:

Fig. 2.3.6.: ZigBee Pin Diagram

2.3.6.1.Pin Description:

1) VCC Power 1.8~3.6V power supply

2) SI - Digital Input - Serial configuration interface, data input

3) SCLK - Digital Input - Serial configuration interface, clock input

4) SO - Digital Output - Serial configuration interface, clock input

· Optional general output pin when CSN is high

5) GDO2 - Digital I/O - Digital output pin for general use

· Test signals· FIFO status signals





· Clear Channel indicator

· Clock output, down-divided from Xosc

· Serial output RX data

6) GND - Ground

7) GDO0 - Digital I/O Digital output pin for general use:

· Test signals

· FIFO status signals

· Clear Channel indicator

· Clock output RX data

· Serial output RX data

· Serial input TX data

Also used as analog test I/O for prototype/production testing

8) Digital Input Serial configuration interface ,chip select

2.3.7.APPLICATIONS:

· Car & Home security system

· Remote keyless entry / Garage door controller

· Wireless game controllers/mouse/keyboard/audio

2.4 LCD MODULE

An HD44780 Character LCD is an industry standard liquid crystal display

(LCD) display device designed for interfacing with embedded systems. These screens

come in common configurations of 8x1 characters, 16x2, and 20x4 among others. The

largest such configuration is 40x4 characters, but these are rare and are actually two

separate 20x4 screens seamlessly joined together. The low power supply (2.7 to 5.5v)

of hd44780.

These screens are often found in copiers, fax machines, laser printers, industrial

test equipment, networking equipment such as routers and storage devices, etc. These

are not the kind of screens one would find in a cell phone, portable television, etc. They

are limited to text only, with 8 customizable characters.





Character LCD s can come with or without back lights. Back lights can be LED,

fluorescent, or electro luminescent. Here we are used LM20400.The ability to display

numbers, characters,and a few characters. Incorporation of a refreshing controller into

the Lcd, thereby relieving the cpu of the task of refreshing the LCD.Ease of

programming for characters and graphics.

Character LCD s use a standard 16-pin interface. If the screen has a back light,

it will have 16 pins. The pin outs are as follows:

Fig2.4: 16*2 LCD Display

2.4.1.Pin Assignment:

The pin assignment standard for character LCD-modules with a maximum of 80

characters and for character LCD-modules with more than 80 characters. Table, pin

assignment for <=80 character displays.

Pin number Symbol Level I/O Function

1 vs s - - Power supply (GND)

2 V cc - - Power supply (+5V)

3 V ee - - Contrast adjust

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

5 R/W 0/1 I 0 = Write to LCD module1 = Read from LCDmodule

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)

15 LED BL A I/O Battery +

16 LED BL K I/O Battery -

Table.2.4.1: LCD Pin Configuration

Character LCD s can operate in 4-bit or 8-bit mode. In 4 bit mode, pins 7

through 10 are unused and the entire byte is sent to the screen using pins 11 through 14

by sending a at a time.

2.4.2.LCD Command Codes:

1) Clear display screen

2) Return home,

4) Decrement cursor (shift cursor to left).

5) Increment cursor (shift cursor to right).

6)Shift display Here we are used LM20400y right.

7) shift display left.

8) Display off, cursor off.

A Display off, cursor on.

C Display on, cursor off.

E Display on, cursor blinking.

F Display on, cursor blinking.

10 Shift cursor position to left.

14 Shift cursor position to right.

18 Shift the entire display to the left.

1C Shift the entire display to the right.

80 Force cursor to beginning of 1st line.









(Least Significant Bit) is sent first. A Stop Bit (Logic 1) is then appended to the signal

to make up the transmission.

The data sent using this method, is said to be framed. That is the data is framed

between a Start and Stop Bit.

2.5.2.RS-232 Voltage Levels:

• +3 to +25 volts to signify a "Space" (Logic 0)

• -3 to -25 volts for a "Mark" (logic 1).

• Any voltage in between these regions (i.e. between +3 and -3 Volts) is

undefined.The data byte is always transmitted least-significant-bit first. The bits are

transmitted at specific time intervals determined by the baud rate of the serial signal.

This is the signal present on the RS-232 Port of your computer, shown below.

Fig2.5.2.: RS-232 Logic Waveform

2.5.3.RS-232 LEVEL CONVERTER:

Standard serial interfacing of microcontroller (TTL) with PC or any RS232C

Standard device , requires TTL to RS232 Level converter . A MAX232 is used for this

purpose. It provides 2-channel RS232C port and requires external 10uF capacitors.

The driver requires a single supply of +5V.


http://www.arcelect.com/rs232.htm

http://www.bsc.nodak.edu/electron/rs232.htm

http://www.arcelect.com/rs232.htm

http://www.bsc.nodak.edu/electron/rs232.htm








Fig2.5.4(a): RS232

IBM PC/ compatible computers based on x86(8086, 80286, 386, 486 and

Pentium) microprocessors normally have two COM ports. Both COM ports have

RS232 type connectors. Many PCs use one each of the DB-25 and DB-9 RS232

connectors. The COM ports are designated as COM1 and COM2. We can connect the

serial port to the COM 2 port of a PC for serial communication experiments. We use a

DB9 connector in our arrangement.

CHAPTER.3.

3.SOFTWARE FEATURES

3.1.Introduction:

In this chapter the software used and the language in which the program code is

defined is mentioned and the program code dumping tools are explained. The chapter

also documents the development of the program for the application. This program has

been termed as “Source code”. Before we look at the source code we define the two

header files that we have used in the code.





3.2.Tools Used:

Fig3.2.: Keil Software- internal stages

Keil development tools for the 8051 Microcontroller Architecture support every

level of software developer from the professional applications

a)C51 Compiler & A51 Macro Assembler:

Source files are created by the µVision IDE and are passed to the C51 Compiler

or A51 Macro Assembler. The compiler and assembler process source files and create

replaceable object files.

The Keil C51 Compiler is a full ANSI implementation of the C programming

language that supports all standard features of the C language. In addition, numerous

features for direct support of the 8051 architecture have been added.





b)Start µVision:

µVision is a standard Windows application and started by clicking on the

program icon.

c)Create a Project File:

To create a new project file select from the µVision menu Project – New

Project. This opens a standard Windows dialog that asks you for the new project file

name. We suggest that you use a separate folder for each project. You can simply use

the icon Create New Folder in this dialog to get a new empty folder. Then select this

folder and enter the file name for the new project, i.e. Project1. µVision creates a new

project file with the name PROJECT1.UV2 which contains a default target and file

group name. You can see these names in the Project Workspace – Files.

d)Select a Device:

1. Click on the Keil uVision Icon on Desktop

2. The following fig will appear





3. Click on the Project menu from the title bar

4. Then Click on New Project

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

folder sited in either C:\ or D:\

6. Then Click on Save button above.

7. Select the component for u r project. i.e. Atmel……8. Click on the + Symbol beside of Atmel









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

clicking on its blue boarder.

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

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

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





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

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





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

22. Click only one time on option “ADD”

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

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

25. The new window is as follows





26. Then Click “OK”

27. Now Click on the Peripherals from menu bar, and check your required port as

shown in fig below

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







//USERDEFINE DATA TYPES

typedef unsigned char LCDubyte;

//DEFINE PROTOTYPES

static void LCDEnable(void);

void LCDWriteCommand(LCDubyte command);

void LCDWriteData(LCDubyte ascii);

void LCDWriteString(LCDubyte *lcd_string);

static void LCDWriteByte(LCDubyte LCDData);

void LCDInitialize(void);

void LCDDisplayInitializing(void);

void LCDDisplayByte(LCDubyte LCDAdress, LCDubyte Value);

static void LCDReset(void);

#endif

static void LCDEnable(void)

{

LCDEnablePin = HIGH;

Delay(2);

LCDEnablePin = LOW;

}

void LCDWriteCommand(LCDubyte LCDData)

{

LCDRegisterSelectPin = LOW;

LCDWriteByte(LCDData);

}

void LCDWriteData(LCDubyte LCDData)

{

LCDRegisterSelectPin = HIGH;

LCDWriteByte(LCDData);

}

void LCDWriteString(LCDubyte *lcd_string)

{





while (*lcd_string)

{

LCDWriteData(*lcd_string++);

}

}

void LCDInitialize(void)

{

LCDEnablePin = OUTPUTPIN;

LCDRegisterSelectPin = OUTPUTPIN;

LCDDataPort &= 0x0f;

LCDReset();

LCDWriteCommand(0x28);

LCDWriteCommand(0x0C);



}

static void LCDReset(void)

{




}

void LCDDisplayInitializing(void)

{

//LCDubyte i;

LCDWriteString("INITIALIZING....");

//LCDRow2();

//for(i = 0 ; i < 16; i++)

//{

// LCDWriteData(46); // ascii value of '.' in decimanl

Delay(100);

//}







#define DELAY_H

//FUNCTION PROTOTYPE

void Delay(unsigned int time);

//DEFINE USER DEFINED DATATYPE

typedef unsigned char ubyte;

#endif

//--------------------------------------------------------

// LCD port input output pins installation

//---------------------------------------------------------

#ifndef LCD_H

#define LCD_H

#define LCD_DATA P1

#define LOW 0

#define HIGH 1

#define MAX_COLUMNS

16

#define UNDER_LINE_CURSOR_ON

74

#define UNDER_LINE_CURSOR_OFF

75

#define CLEAR_DISPLAY

88

#define BLINKING_CURSOR_ON

83

#define BLINKING_CURSOR_OFF

84

#define SET_CURSOR_HOME

72





#define SET_CURSOR_POSITION

71

#define SET_CONTRAST

80

#define SET_BACKLIGHT_BRIGHTNESS 153

#define GENERALPURPOSE_OUTPUT_ON

87

#define GENERALPURPOSE_OUTPUT_OFF

86

#define BACKLIGHT_ON

66

#define BACKLIGHT_OFF

70

#define CURSOR_LEFT

76

#define CURSOR_RIGHT

77

//lcd commands

//lcd commands

#define LCD_CLEAR_DISPLAY

0X01

#define LCD_CURSOR_ON

0x0E

#define LCD_CURSOR_OFF

0x0C

#define LCD_BLINKING_ON

0x0F

#define LCD_BLINKING_OFF

0x0C

#define LCD_CURSOR_HOME

0x02

#define LCD_CURSOR_LEFT

0x10





#define LCD_CURSOR_RIGHT

0x14

sbit RS = P3^2;

sbit E = P3^3;

void SignOnMessage();

void delay(unsigned int);

void LcdInit();

void LCDInstWrite(unsigned char instruction);

void LCDDataWrite(unsigned char character);

void LCDGotoXY(unsigned char X, unsigned char Y);

//void LCDPutText(char *datastr);

LCDPutChar(char datachar);

void LCDWriteLine(unsigned char LineNo, char *datastr, unsigned char Alignment);

void LCDClearLine(unsigned char LineNo);

void LCDCursorON();

void LCDCursorOFF();

void LCDClearLine(unsigned char LineNo);

void SendByteSerial(unsigned char lcdstr);

unsigned char LCD_CurrentX=1;

unsigned char LCD_CurrentY=1;

unsigned char *ptr,i;

unsigned char *lines[]={

"\r*******************************************\

n\r",

"** Welcome to E-Notice Board **\n\r",

"*******************************************\n\

r",

"** Operation Instructions.... **\n\n\r",





"** Press 1 to Clear Display **\n\r",

"** Press 2 to Display String on 1st Line**\n\r",

"** Press 3 to Display String on 2nd Line**\n\r",

"** Press 4 to Enter String to Display **\n\r",

"*******************************************\n\

r",

"\n\n\rPress Now:\n\n\r"};

unsigned char *inst[]={

"Lcd On & Initialised...\n\r",

"Cleared LCD Display...\n\r",

"String will Display in 1st Line...\n\r",

"String will Display in 2nd Line...\n\r",

"Please enter the String and Press Return...\n\r",

"LCD Turned OFF...\n\r"};

#endif

//---------------------------------------------------

// Main function starts here

//---------------------------------------------------

/*-----------------------------------------------------------------------------

serial coomunication.c : Demonstration of serial communication - A ECHO program

Designed for 8051 running at 11.0592Mhz

communication between PC and microcontroller.

RS232 serial specification

9600 baud rate

8-bit

1- start bit

1-stop bit

parity none

compile the program in Keil uVision Compiler.

Note: Hyper Terminal / Terminal v1.9b software for communication

operation: receives data from PC (or any serial device) and transmitt





same data back to PC- A ECHO program

feedback appreciated: [email protected]

------------------------------------------------------------------------------*/

//INCLUDES

#include<reg51.h> //Includes definition of 89c51

#include <intrins.h>

#include <string.h>

#include <stdio.h>

#include "lcd.h"

#include "delay.h"

//DEFINE CONSTANT

#define Baud_rate 0xFD // BAUD RATE 9600

//#define LCDDataPort P2

//DEFINE PROTOTYPES

void main(void);

void SerialInitialize(void);

void SendByteSerially(unsigned char ascii);

unsigned char ReceiveByteSerially(void);

void send_string(unsigned char *ptr);

//FUNCTIONS

void main(void)

{

unsigned char lcdstr[50],lk,serialdata,lcdcommand; // DECLARE

serialdata VARIABLE AS UNSIGNED CHAR

//unsigned char *lok[21];

SerialInitialize(); // CALL ROUTINE TO INITIALIZE

SERIAL PORT

LcdInit();

SignOnMessage();





delay(0xffff);

for(i=0;i<=9;i++)

{

send_string(lines[i]);

//LCDPutChar(serialdata);

}

for(;;) // INFINITE LOOP

{

//serialdata = ReceiveByteSerially(); // RECEIVE DATA FROM

SERIAL PORT (PC)

//SendByteSerially(serialdata); // SEND DATA BACK TO PC

lcdcommand= ReceiveByteSerially();

switch(lcdcommand)

{

case '1':

LCDInstWrite(LCD_CLEAR_DISPLAY);

send_string("Cleared LCD Display...\n\r");

break;

case '2':


LCDWriteLine(1,"ESSENCE SOCIETY",2);

send_string("String will Display in 1st

Line...\n\r");

LCDInstWrite(0x80);

break;

case '3':


LCDWriteLine(2,"ANANTAPUR",2);

send_string("String will Display in 2nd

Line...\n\r");

LCDInstWrite(0xC0);







} // END OF MAIN FUNCTION

void SerialInitialize(void) // INITIALIZE SERIAL PORT

{

TMOD = (( TMOD & 0x0F) | 0x20); // Timer 1 IN MODE 2 -AUTO

RELOAD TO GENERATE BAUD RATE

SCON = 0x50; // SERIAL MODE 1, 8-DATA BIT 1-START

BIT, 1-STOP BIT, REN ENABLED

TH1 = Baud_rate; // LOAD BAUDRATE TO TIMER

REGISTER

TR1 = 1; // START TIMER

}

void SendByteSerially(unsigned char serialdata)

{

SBUF = serialdata; // LOAD DATA TO SERIAL BUFFER

REGISTER

while(TI == 0); // WAIT UNTIL

TRANSMISSION TO COMPLETE

TI = 0; // CLEAR TRANSMISSION

INTERRUPT FLAG

}

void SendByteSerial(unsigned char serial)

{

SBUF = serial; // LOAD DATA TO SERIAL BUFFER

REGISTER

while(TI == 0); // WAIT UNTIL

TRANSMISSION TO COMPLETE

TI = 0; // CLEAR TRANSMISSION

INTERRUPT FLAG

}

unsigned char ReceiveByteSerially(void)

{

while(RI == 0); // WAIT UNTIL DATA IS

RECEIVED





RI = 0; // CLEAR FLAG

return SBUF; // RETURN SERIAL DATA

}

void send_string(unsigned char *str)

{

while(*str)

{

SendByteSerially(*str++);

}

}

/

**********************************************************************

******

LCD INTIALISATIONS

**********************************************************************

*******/

void LcdInit()

{

// LCDInstWrite(0X30);

// delay(0xff);

// LCDInstWrite(0x30);

// delay(0xff);

// LCDInstWrite(0x30);

// delay(0xff);

LCDInstWrite(0x38);

LCDInstWrite(0x0C);

LCDInstWrite(0x01);

LCDInstWrite(0x06); // Auto increment cursor position

}

void LCDInstWrite(unsigned char instruction)

{





RS = 0;

E = 0;

LCD_DATA = instruction;

E = 1;

// _nop_();

// _nop_();

// _nop_();

delay(0xf);

E = 0;

delay(0xff);

}

void LCDDataWrite(unsigned char character)

{

RS = 0;

E = 0;

LCD_DATA = character;

E = 1;

RS = 1;

// _nop_();

// _nop_();

// _nop_();

delay(0xf);

E = 0;

delay(0x1ff);

}

void LCDGotoXY(unsigned char X, unsigned char Y)

{

if(X < 1 || X > MAX_COLUMNS)

return;

switch(Y)

{











The above ciricuit diagram shows “Wireless Electronic Notice Board”.

The above diagram consists of

1.Microcontroller.(AT89S52).

2. LCD.

3. MAX232.

4. DB9 connector.

The connections of the project are explained here. LCD they have 16 pins in

that 1st ,3rd ,and 5th pins are connected to Ground. Reset and Enable pins are connected

to Microcontroller P3.2 and P3.3. LCD seven data pins are connected to

Microcontroller P1.0-P1.7.

The Microcontroller 31st and 40th pins are connected to the VCC and the 18th

and 19th pins are connected to crystal oscillator through capacitors to ground, 20 th pin

also connected to the ground. Whereas the pins 10th and 11th of the microcontroller are

connected to the pins 12th and 11th of MAX232.

The MAX232 pins 6th and 15th are connected to the ground, 1st and 3rd pins are

connected to the capacitor C3, 4th and 5th pins are connected to the C4, 2nd and 16th pins

are connected to VCC through to capacitor C1 and 13th and 14th pins are connected to

DB9 Serial Port pins of 2nd(Rxd) and 3rd(Txd).Serial Port 5th pin is connected to the

Ground.

CHAPTER.6.









6. Above fig shows the whenever we press the 3 button in the keyboard the

respective command will seen on hyper terminal as well as respective function

seen on the LCD.

7. Whenever we press the 4 button in the keyboard the respective command will

follows by the LCD that is “please enter the string and press return”.

8. For example we can enter the string “Welcome” and then press the “Shift+4”

the String will be displayed on the LCD Board.





CHAPTER.7.

7.CONCLUSION

• This project can be successfully implemented we can transferring the data

between the two devices through Wireless Communication.

• This project can be used in Bus and Railway stations, Offices and Colleges.





CHAPTER.8.

8.FUTURE SCOPE

The project will be extended by means of controlling the several devices

connected to the target board. In future we can control the device from remote end such

as pc using by developing webpage.





CHAPTER.9.

9.REFERENCES

Text Books:

Microcontroller and Embeeded systems By Mazidi.

Working with Radio Frequency By Cruis Leanardo.

Radio Frequency Applications By Morris Hamington.

Website:

www.howstuffworks.com

www.answers.com

www.radiotronix.com

Magazines:

Electronics for you

Electrikindia

Let us Go Wireless

Documents

b.naresh-9494406519 Sri Sai College of Eng & Technology (2)