final report home automation - all

7/30/2019 Final Report Home Automation - ALL

1/80

CHAPTER I

INTRODUCTION

Some of the main devices used in embedded products are Microprocessors

and Microcontrollers, Microprocessors are commonly referred to as general

purpose processors as they simply accept the inputs, process it and give the

output. In contrast, a microcontroller not only accepts the data as inputs but also

manipulates it, interfaces the data with various devices, controls the data and thus

finally gives the result. As everyone in this competitive world prefers to make the

things easy and simple to handle, this project sets an example to great extent.

Today is the trend of Wireless technology. Nowadays, we are seeing that

everything has gone wireless. In this case, it becomes necessary to make a System

by which we can control appliances in our home by sending SMS to GSM

Modem. For example, if we send certain message to GSM Modem, then Fan of

particular room will get switched on and if we again send a message, then Fan

can be switched off. This means that basically we are controlling our home

appliances with the movement of our fingers that become messages. This project

we can mainly use in Homes, Agricultural Farms. The fact that we are using the

GSM technology to control devices is one of the new technologies in the

embedded field to make the communication between Microcontroller and mobile.

This project is a remote home automation with MODEM connected to it, so if the

user wants to control some appliances, he or she will send the messages in SMS

format, the MODEM in the automation system will receive the message and

update the display according to the message and turn off or on the particular

device that we want to access. For every message received from the user mobile,

Microcontroller will work accordingly.

GSM based Home Automation System implements the emerging

applications of the GSM technology. Using GSM networks, a control system has

been proposed that will act as an embedded system which can monitor and1


2/80

control appliances and other devices locally using built-in input and output

peripherals.

GSM (Global System for Mobile Communications): It is a cellular

communication standard.

SMS (Short Message Service): It is a service available on most digital mobile

phones that permit the sending of short messages (also known as text messaging

service), that can be used to perform specific operations that we want to perform

by interfacing the GSM Modem with Microcontroller.

2


3/80

CHAPTER-II

LITERATURE SURVEY

2.1 MOTIVATION:

In present digitalized world, the exploit of GSM and SMS is popular.

Today the Electronics world is changing so fast then we have to get in sync with

the world so that we can learn new technologies that are real fascinating. So, we

have taken first step in this to design GSM based Home Automation System. By

sitting in another room, you can operate Lights and Fans of another room by

sending messages to the GSM Modem.

From the past many years we are seeing the Automation is being done

using various Sensors. So we were thinking that if somehow we can use Wireless

technique instead of sensors, so we come to the conclusion to design this Project

which will eliminate the work of Sensors with less manual operation. If you have

gone to Market and forgot to switch off the Fan, then you can just do the same by

sending message to the number that has been put in the GSM Modem.

2.2 BACKGROUND:

Market research analysts are predicting that the wireless technologies will

eventually become more widespread than the various wired solutions. The

wireless communications present the ideal solution for the home network .This

increasing demand of getting wireless can be seen not only in the field

communication but also in the transferring information and data. The cell phones

which are the best example of wireless data and voice transfer can be used for

many other purposes that can replace the traditional system. One simple way of

using this wireless communication is to use a simple cell phone for sending

messages. The GSM modem used at the receiver end is used to receive the3


4/80

messages and LCD to display them. As we are using mobile for sending

messages, its easy to handle and operate. As it's a wireless transmission the

system has very less errors and maintenance. Also, we are dealing with digital

signals, so loss of data and factors like Noise are negligible.

2.3 AIM:

To design and implement a GSM based Wireless Home Automation

System using 8051 Microcontroller coded in Embedded C Language.

2.4 REQUIREMENT ANALYSIS:

2.4.1 Hardware requirements

The components those are required for Wireless Home AutomationSystem project is given below.

1. Microcontroller (AT89S52).

2. MAX 232.

3. DB9 or RS232 connector.

4. Power Supply.

5. LCD Display (16x2).

6. GSM Modem.

7. SIM.

4


5/80

2.4.2 Software requirements

1. KEIL Vision 4 IDE C51 Embedded Cross Compiler.

2. Proteus 7.8 Simulator.

3. 8051 ISP Programmer

2.5 SCOPE:

The scope of this project is to introduce a new technology for home

automation system using GSM. A user can send a message from anywhere in theworld. Multilingual display can be another added variation of the project.

Graphical display can also be considered as a long term but achievable and

targetable output. Also, we can extend this project to make it more fascinating for

systems like Home and Industrial Security system. It can also be used in Military

applications for remote bomb triggering, launch missiles etc.

2.6 ADVANTAGES:

Accessible everywhere.

Low cost, reliable and high accuracy.

Not much manual effort.

Give feedback response to the sender.

Saves Time, Energy and finally Environment friendly.

5


6/80

CHAPTER - III

DESIGN METHODOLOGY

3.1 HARDWARE SYSTEM DESIGN:

3.1. 1 Block Level Design

The block diagram of GSM based message display system is given below

Fig 3.1: Functional block diagram of Wireless Home Automation.

6


7/80

3.1.2 Selection Of Hardware:

The hardware selected must be such a way that:

Low cost

Low power consumption, small, fast

Continually reacts to changes in the systems environment

Must compute certain results in real-time without delay

Simple design

Easy maintainability and interoperability

Bug-free/Correctness, safety, many more.

3.1.3 Design Considerations Of Microcontroller

WHY AT89S52?

The system requirements and control specifications clearly rule out the

use of 16, 32 bit microcontrollers.

It contains non-volatile 64KB Flash program memory that is bothparallel programmable and serial In-System and In-Application

Programmable.

In-System Programming (ISP) allows the user to download new code

while the microcontroller sits in the application.

Its ROM is double of the ROM of 8051 i.e. 8KB and its RAM is 256

bytes. It has 3 timers and a Serial port that allows Serial Communication.

3.1.3 Microcontroller 8051

The 8051 is an 8 bit microcontroller originally developed by Intel in 1980.

It is one of the most popular microcontrollers in the world for its high

performance, rich instruction set and low cost. This device is a Single-Chip 8-Bit

Microcontroller manufactured in an advanced CMOS process and is a derivative

7


8/80

of the 8051 microcontroller family. The instruction set is 100% compatible with

the 8051 instruction set. Three criteria in choosing the microcontrollers are as

follows:

1. Meeting the computing needs of the task at hand efficiently and cost

effectively.

2. Availability of software development tools such as compliers,

assemblers, and debuggers.

3. Wide availability and reliable sources of the microcontroller.

Some of the features that have made the 8051 popular are:

64 KB on chip program memory.

128 bytes on chip data memory (RAM).

4 register banks.

128 user defined software flags.

Four 8-bit data bus

16-bit address bus

32 general purpose registers each of 8 bits

16 bit timers (usually 2, but may have more, or less).

3 internal and 2 external interrupts.

Bit as well as byte addressable RAM area of 16 bytes.

Four 8-bit ports, (short models have two 8-bit ports).

16-bit program counter and data pointer.

8


9/80

1 Microsecond instruction cycle with 12 MHz Crystal.

8051 models may also have a number of special, model-specific features,

such as UARTs, ADC, Op Amps, etc...

3.1.3.1 Pin Description of AT89S52

Fig 3.1: 40 Pin Description of 8051.

9


10/80

3.1.3.2 Internal architecture of AT89S52

The AT89S52 contains a non-volatile 64KB Flash program memory that is

both parallel programmable and serial In-System Programmable. In-System

Programming (ISP) allows the user to download new code while the

microcontroller sits in the application.

8051 is the first controller developed by Intel. It is 8-bit microcontroller

meaning it can process 8 bits of data at a given time because it has only 8 data

lines.Nowadays, there are many variant of 8051 manufactured by various

Electronics companies but the basic structure of all the variant of 8051 is similar

to that of 8051 that was developed by the Intel. The variants of 8051 are

AT89C51, AT89C52, AT89S51, AT89S52 etc. These are manufactured by

Atmel. In the same way, some other companies like Motorola, Microchip, and

Dallas Semiconductors etc also manufacture the microcontrollers that are variants

of 8051. These companies have permission that they can change the memory

specifications but the basic structure should remain same as Intels 8051 and it

must have 40 pins. Intel has the first copyright of 8051; if any company wants to

change the design of controller then at first it needs the permission from Intel.

10


11/80

The internal architecture of AT89S52 microcontroller:

Fig 3.2: Internal architecture of AT89S52.

11


12/80

3.1.3.2.1 I/O ports:

All 8051 microcontrollers have 4 I/O ports each comprising 8 bits which

can be configured as inputs or outputs. Accordingly, in total of 32 input/output

pins enabling the microcontroller to be connected to peripheral devices are

available for use.Pin configuration, i.e. whether it is to be configured as an input(1) or an output (0), depends on its logic state. In order to configure a

microcontroller pin as an input, it is necessary to apply logic zero (0) to

appropriate I/O port bit. In this case, voltage level on appropriate pin will be 0.

The 4I/O ports of 8051 are designated as port 0, port 1, port 2, and port 3.

All these I/O ports have different functions and conditions while connecting to

external peripherals.

3.1.3.2.1.a Port 0 (P0)-

The P0 port is characterized by two functions. If external memory is used

then the lower address byte (addresses A0-A7) is applied on it. Otherwise, all bits

of this port are configured as inputs/outputs. The other function is expressed

when it is configured as an output. Unlike other ports consisting of pins with

built-in pull-up resistor connected by its end to 5 V power supply; pins of this

port have this resistor left out. If any pin of this port is configured as an input then

it acts as if it floats. Such an input has unlimited input resistance and

undetermined potential. When the pin is configured as an output, it acts as an

open drain. By applying logic 0 to a port bit, the appropriate pin will be

connected to ground (0V). By applying logic 1, the external output will keep on

floating. In order to apply logic 1 (5V) on this output pin, it is necessary to built

in an external pull-up resistor.

12


13/80

3.1.3.2.1.b Port 1 (P1)-

P1 is a true I/O port, because it doesn't have any alternative functions as is

the case with P0, but can be configured as general I/O only. It has a pull-up

resistor built-in and is completely compatible with TTL circuits.

3.1.3.2.1.c Port 2 (P2)-

P2 acts similarly to P0 when external memory is used. Pins of this port

occupy addresses intended for external memory chip. This time it is about the

higher address byte with addresses A8-A15. When no memory is added, this port

can be used as a general input/output port showing features similar to P1.

3.1.3.2.1. d Port 3 (P3)-

All port pins can be used as general I/O, but they also have an alternative

function. In order to use these alternative functions, a logic one (1) must be

applied to appropriate bit of the P3 register. In terms of hardware, this port is

similar to P0, with the difference that its pins have a pull-up resistor built-in.

3.1.3.2.2 Interrupts controls:

There are 7 kinds of interrupt controllers that 8051 handles. They are as

follows.

1. INT0 external interrupt.

2. INT1 external interrupt.

3. Timer 0

4. Timer 1

5. Reset.

6. Transmitted interrupt (TXD).

13


14/80

7. Received interrupt (RXD).

There are two types of external hardware interrupts. Pin 12 (P3.2) and pin 13

(P3.3) of the 8051, designated as INT0 and INT1, are used as external hardware

interrupts. Upon the activation of these pins, the 8051 gets interrupted in

whatever it is doing and jumps to the vector table to perform the interrupt service

routines (ISR).

Timer 0 and timer 1 interrupts can be used in pooling method. In this method,

we have to wait until the TF is raised. The problem with this method is that the

microcontroller is tied down the controller. If the timer interrupt in the IE registeris enabled, whenever the timer rolls over, TF is raised, and the microcontroller is

interrupted in whatever it is doing, and jumps to the interrupts vector table to

service the ISR.

Reset pin is an input pin and is active high (normally low). Upon applying

a high pulse to this pin, the microcontroller will reset and terminate all activities.

This is often referred to as power-on reset. In order for RESET input to be

effective, it must have a minimum duration of two machine cycles. In other

words, the high pulse must be high for a minimum of two machine cycles before

it is allowed to go low. TXD and RXD are serial communication interrupts.

3.1.3.2.3 Bus Controls

The main bus controllers available in 8051 are ALE, EA, RST and PSEN.

ALE (Address Latch Enable):

It is output pulse for latching the low byte of the address during an access

to external memory. In normal operation, ALE is emitted twice every machine

cycle, and can be used for external timing or clocking. Note that one ALE pulse is

skipped during each access to external data memory. ALE can be disabled by

14


15/80

setting SFR auxiliary.0. With this bit set, ALE will be active only during a

MOVX instruction.

EA (External Access Enable/Programming Supply Voltage):

EA must be externally held low to enable the device to fetch code from

external program memory locations. If EA is held high, the device executes from

internal program memory. The value on the EA pin is latched when RST is

released and any subsequent changes have no effect. This pin also receives the

programming supply voltage (VPP) during Flash programming.

RST (Reset):

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

resets the device. An internal resistor to VSS permits a power-on reset using only

an external capacitor to VCC.

PSEN (Program Store Enable):This is the pin to read strobe to external program memory. When executing

code from the external program memory, PSEN is activated twice each machine

cycle, except that two PSEN activations are skipped during each access to

external data memory. PSEN is not activated during fetches from internal

program memory.

3.1.3.2.4 Memory organization

The 8051 has two types of memory and these are Program Memory and

Data Memory. Program Memory (ROM) is used to permanently save the program

being executed, while Data Memory (RAM) is used for temporarily storing data

and intermediate results created and used during the operation of the

microcontroller. Depending on the model in use (we are still talking about the

15


16/80

8051 microcontroller family in general) at most a few Kb of ROM and 128 or 256

bytes of RAM is used. All 8051 microcontrollers have a 16-bit addressing bus

and are capable of addressing 64 kb memory. It is neither a mistake nor a big

ambition of engineers who were working on basic core development. It is a

matter of smart memory organization which makes these microcontrollers a real

programmers goody.

3.1.3.2.5 Registers in 8051

In the CPU, registers are used to store information temporarily. Thatinformation could be a byte of data to be processed, or an address pointing to the

data to be fetched. The vast majority of 8051 registers are 8- bit registers. In the

8051 there is only one data type: 8 bits. With an 8-bit data type, any data larger

than 8 bits must be broken into 8- bit chunks before it is processed. The most

widely used registers of the 8051 are A(Accumulator), B, and SPF (special

function registers) and PSW (Program Status Word).

A register is a general-purpose register used for storing intermediate results

obtained during operation. Prior to executing an instruction upon any number or

operand it is necessary to store it in the accumulator first. All results obtained

from arithmetical operations performed by the ALU are stored in the

accumulator. Data to be moved from one register to another must go through the

accumulator. In other words, the A register is the most commonly used register

and it is impossible to imagine a microcontroller without it. More than half

instructions used by the 8051 microcontroller use somehow the accumulator.

Multiplication and division can be performed only upon numbers stored in the A

and B registers. All other instructions in the program can use this register as a

spare accumulator (A).

16


17/80

3.1.3.2.5.a R Registers (R0-R7)

This is a common name for 8 general-purpose registers (R0, R1, R2 ...R7).

Even though they are not true SFRs, they deserve to be discussed here because of

their purpose. They occupy 4 banks within RAM. Similar to the accumulator,

they are used for temporary storing variables and intermediate results during

operation. Which one of these banks is to be active depends on two bits of the

PSW Register. Active bank is a bank the registers of which are currently used.

3.1.3.2.5.bSFR (Special Function Registers)

Special Function Registers (SFRs) are a sort of control table used for

running and monitoring the operation of the microcontroller. Each of these

registers as well as each bit they include, has its name, address in the scope of

RAM and precisely defined purpose such as timer control, interrupt control, serial

communication control etc. Even though there are 128 memory locations

intended to be occupied by them, the basic core, shared by all types of 8051

microcontrollers, has only 21 such registers.

3.1.3.2.5.c PROGRAM STATUS WORD (PSW):

CY: Carry out from accumulator MSB of ALU operand

AC: Auxiliary carry for BCD operations

FO: General purpose

RS1 & RS0: For register banks selection ( RB0-RB3)

OV: Overflow flag

17


18/80

P: Parity of accumulator set by hardware to 1 if it contains odd no of 1s.

Carry flag:

Carry flag is set whenever there is carry out from the MSB. This flag is

after 8bit ADD/SUB operation. It can also be set to 1 or 0 directly using SETB C

or CLR C.

Auxiliary carry:

If there is a carry from D3 to D4 position during Add/Sub

operation, this bit will set. Otherwise, it is cleared. This flag is used for BCD

operations.

Parity flag reflects the number of 1s in A. If A contains an odd

number of 1s, then P=1. Therefore P=0, if A has an even number of 1s.

Overflow flag:

This flag is set whenever the result of a signed number operation is too

large to be accommodated in 7 bits, causing the higher order bit to overflow into

the sign bit.

3.1.3.2.6 Oscillator:

The microcontroller used in this project, P89C51RD2FN requires a baud

rate of 9600. To acquire this baud rate, an 11.0592 MHz crystal must be

connected between 19th and 20th pins of controller. The determination of machine

cycle frequency and Baud rate is as follows.

MCF = (XTL freq / 12)

= (11.0592 * 10^6) / 12 = 921.6 KHz

Baud rate = MCF/32 = (921.6 10^3) / 32 = 28800 Hz

Where MCF = Machine Cycle Frequency, XTL = Crystal18


19/80

To synchronize with timer1 (TH1) to set the baud rate as 9600 we need to

set those register value as -3 (decimal) or FD (Hexadecimal) so as to divide the

baud rate i.e.. 28800Hz should be dividing with the decimal value of TH1 to get

9600 value.

Fig 3.3: Oscillator Connections

C1, C2 = 33pF.

3.1.3.3 Features:

80C51 Central Processing Unit

Speed up to 20MHz with 6-clock cycles per machine cycle

(40MHz equivalent performance), up to 33MHz with 12 clocks per

machine cycle

Four interrupt priority levels

8-Bit program status word

8 bit stack pointer

Two 16 bit timer/counter T0 & T1

Control registers TCON, TMOD and SCON, PCON and IP & IE

oscillator & clock circuits.

19


20/80

3.1.4 SERIAL COMMUNICATION

3.1.4.1 Introduction

In order to connect microcontroller to a modem or a pc to modem a serial

port is used. Serial is a very common protocol for device communication that is

standard on almost every PC. Most computers include two RS-232 based serial

ports. Serial is also a common communication protocol that is used by many

devices for instrumentation; numerous GPIB-compatible devices also come with

an RS232 port. Furthermore, serial communication can be used for data

acquisition in conjunction with a remote sampling device.

Typically, serial is used to transmit ASCII data. Communication is

completed using 3 transmission lines. (1) Ground, (2) Transmit and (3) Receive.

Since serial is asynchronous, the port is able to transmit data on one line while

receiving data on another. Other lines are available for handshaking, but are not

required. The important serial characteristics are baud rate, data bits, stop bits,

and parity. For two ports to communicate, these parameters much match.

Serial communication is a popular means of transmitting data between a

computer and a peripheral device such as a programmable instrument or even

another one bit at a time, over a single communication line to a receiver. You can

use this method when data transfer rates are low or you must transfer data over

long distances. Serial communication is popular because most computers have

one or more serial ports, so no extra hardware is needed other than a cable to

connect the instrument to the computer or two computers together.

Any device you connect to the serial port will need the serial transmission

converted back to parallel so that it can be used. In serial communication, the data

will be sent from one system to another in bit by bit notation. Serial Ports come in

two sizes, there are the D-Type 25 pin connector and the D-Type 9 Pin

connector both of which are male on the back of the PC, and thus you will require

20


21/80

a female connector on your device. The RS-232 and RS-485 come under serial

communication.

3.1.4.2 Baud Rate:

It is a speed measurement for communication. It indicates the number of

bit transfers per second. For example, 300 baud is 300 bits per second. When a

clock cycle is referred it means the baud rate. For example, if the protocol calls

for a 4800 baud rate, then the clock is running at 4800Hz. This means that the

serial port is sampling the data line at 4800Hz. Common baud rates for telephone

lines are 12200, 28800 and 33600. Baud rates greater than these are possible, but

these rates reduce the distance by which devices can be separated.

3.1.5 HARDWARE DESIGN OF LCD

The LCD (Liquid Crystal Display) used to display the output to the user in the

form of GUI (Graphic User Interface) and a mono chromatic display. LCD used

in this project is JHD162A series. There are 16 pins in all. They are numbered

from left to right 1 to 16 (if you are reading from the backside). LCD shown

above is marked to indicate which the 1st pin was and which the 16th was.

In our project, we use a JHD162A LCD Display which has 2 rows and 16

characters. It contains internal 1 byte latch. It has a better contrast and a wider

viewing angle. These displays contain two internal byte-wide registers, one for

command and second for characters to be displayed. There are three control

signals called R/W, RS and EN. Select By making RS signal 0 you can send

different commands to display. These commands are used to initialize LCD, to

display pattern, to shift cursor or screen etc. You can see the markings right next

to 1st and 16th pins. The 16x2 LCD with connections is as given below.

21


22/80

Fig 3.4: Pin configuration of LCD

3.1.5.1 LCD screen:-

LCD screen consists of two lines with 16 characters each. Each character

consists of 5x7 matrixes. Contrast on display depends on the power supply

voltage and whether messages are displayed in one or two lines. For that reason,

variable voltage 0-VDD is applied on pin marked as VEE. Trimmer potentiometer is

usually used for that purpose. Some versions of displays have built in backlight

(blue or green diodes). When used during operating, a resistor for current

limitation should be used.

The main control pins on JHD162A are data lines, read or write and enable.

LCD is finding wide spread use replacing LEDs because of the following reasons:

1. The ability to display numbers, characters and graphics. This is in contrast

to LEDs, which are limited to numbers and a few characters.

2. Incorporation of a refreshing controller into the LCD, thereby relieving the

CPU of the task of refreshing the LCD. In contrast, the LED must be

refreshed by the CPU to keep displaying the data.

3. Ease of programming for characters and graphics.22


23/80

4. These components are specialized for being used with the

microcontrollers, which means that they cannot be activated by standard IC

circuits. They are used for writing different messages on a miniature LCD.

Fig 3.5: 16x2 LCD Display

3.1.5.1.a Data lines (D0-D7):

The data lines are connected to the parallel port of the microcontroller.

These 8 lines are responsible for data and commands transfer depends upon RSpin. If RS = 0, then Command Register gets selected otherwise Data Register.

3.1.5.1.b Read and write:

Generally, we always use the LCD to show things on the screen. However,

in some rare cases, we may need to read from the LCD what it is displaying. In

such cases, the R/W pin is used. However, this function is beyond the scope of

post and will not be explained. For all practical purposes, the R/W pin has to be

permanently connected to GND.

3.1.5.1.c Enable Pin:

The enable pin has a very simple function. It is just the clock input for the

LCD. The instruction or the character data at the data pins (D0-D7) is processed

by the LCD on the falling edge of this pin. The Enable pin should be normally

23


24/80

held at Vcc by a pull up resistor. When a momentary button switch is pressed, the

Pin goes low and back to high again when you leave the switch. Your instruction

or character will be executed on the falling edge of the pulse. (i.e. the moment the

switch closes).

3.1.5.1.d Register Select (RS) pin:

The LCD has basically two operating modes:Instruction mode and

Character Mode. Depending on the status of this pin, the data on the 8 data pins

(D0-D7) is treated as either an instruction or as character data. You have to

activate the command mode if you want to give an Instruction to the LCD. To set

the LCD in Instruction mode, you set the 4th pin of the LCD (R/S) to GND. To

put it in character mode, you connect it to Vcc.

24


25/80

To start with LCD the user should initialize it first which should be programmed

with its LCD commands. The LCD commands are given:

25


26/80

CODE COMMANDS TO THE LCD

1 Clear display screen

2 Return home

4 Shift cursor to left

5 Shift display right

6 Shift cursor to 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 off, cursor blinking

10 Shift cursor position to left

14 Shift cursor position to right

18 Shift entire display left

1c Shift entire display right

80 Force cursor to begin in 1st row

C0 Force cursor to begin in 2nd row

26


27/80

3.1.6 GSM MODULE:

GSM/GPRS module is used to establish communication between a

computer and a GSM-GPRS system. Global System for Mobile communication

(GSM) is an architecture used for mobile communication in most of the countries.

Global Packet Radio Service (GPRS) is an extension of GSM that enables higher

data transmission rate. GSM/GPRS module consists of a GSM/GPRS modem

assembled together with power supply circuit and communication interfaces (like

RS-232, USB, etc) for computer. The MODEM is the soul of such modules.

Fig 3.9: GSM/GPRS Module

3.1.6.1 Wireless MODEMs:

Wireless MODEMs are the MODEM devices that generate, transmit or

decode data from a cellular network, for establishing communication between the

cellular network and the computer. These are manufactured for specific cellular

network (GSM/UMTS/CDMA) or specific cellular data standard

(GSM/UMTS/GPRS/EDGE/HSDPA) or technology (GPS/SIM). Wireless

27


28/80

MODEMs like other MODEM devices use serial communication to interface with

and need Hayes compatible AT commands for communication with the computer

(any microprocessor or microcontroller system).

3.1.6.2 GSM/GPRS MODEM

GSM/GPRS MODEM is a class of wireless MODEM devices that are

designed for communication of a computer with the GSM and GPRS network. It

requires a SIM (Subscriber Identity Module) card just like mobile phones to

activate communication with the network. Also they have IMEI (International

Mobile Equipment Identity) number similar to mobile phones for their

identification. A GSM/GPRS MODEM can perform the following operations:

1. Receive, send or delete SMS messages in a SIM.

2. Read, add, search phonebook entries of the SIM.

3. Make, Receive, or reject a voice call.

The MODEM needs AT commands, for interacting with processor or

controller, which are communicated through serial communication. These

commands are sent by the controller/processor. The MODEM sends back a result

after it receives a command. Different AT commands supported by the MODEM

can be sent by the processor/controller/computer to interact with the GSM and

GPRS cellular network.

3.1.6.3 GSM/GPRS Module

A GSM/GPRS module assembles a GSM/GPRS modem with standard

communication interfaces like RS-232 (Serial Port), USB etc., so that it can be

easily interfaced with a computer or a microprocessor / microcontroller based

28
http://www.engineersgarage.com/tutorials/at-commands


29/80

system. The power supply circuit is also built in the module that can be activated

by using a suitable adaptor.

Fig 3.11: GSM module

3.1.6.4 Mobile Station (Cell phones and SIM)

A mobile phone and Subscriber Identity Module (SIM) together form a

mobile station. It is the user equipment that communicates with the mobile

network. A mobile phone comprises of Mobile Termination, Terminal Equipment

and Terminal Adapter.

29


30/80

Mobile Termination is interfaced with the GSM mobile network and is

controlled by a baseband processor. It handles access to SIM, speech encoding

and decoding, signaling and other network related tasks. The Terminal Equipment

is an application processor that deals with handling operations related to keypad,

screen, phone memory and other hardware and software services embedded into

the handset. The Terminal Adapter establishes communication between the

Terminal Equipment and the Mobile Termination using AT commands. The

communication with the network in a GSM/GPRS mobile is carried out by the

baseband processor.

3.1.6.5 Applications of GSM/GPRS module

The GSM/GPRS module demonstrates the use of AT commands. They can

feature all the functionalities of a mobile phone through computer like makingand receiving calls, SMS, MMS etc. These are mainly employed for computer

based SMS and MMS services.

3.1.6.6 AT Commands

AT commands are used to control MODEMs. AT is the abbreviation for

Attention. These commands come from Hayes commands that were used by the

Hayes smart modems. The Hayes commands started with AT to indicate the

attention from the MODEM. The dial up and wireless MODEMs (devices that

involve machine to machine communication) need AT commands to interact with

a computer. These include the Hayes command set as a subset, along with other

extended AT commands.

30


31/80

AT commands with a GSM/GPRS MODEM or mobile phone can be used to

access following information and services:

1. Information pertaining to mobile device or MODEM and SIM card.

2. SMS services.

3. MMS services.

4. Fax services.

5. Data and Voice link over mobile network.

The Hayes subset commands are called the basic commands and the commands

specific to a GSM network are called extended AT commands.

3.1.6.7 Command, Information response and Result Codes:

The AT commands are sent by the computer to the MODEM/ mobile phone. The

MODEM sends back an Information Response i.e. the information requested by

or pertaining to the action initiated by the AT command. This is followed by aResult Code. The result code tells about the successful execution of that

command.

31


32/80

There are also unsolicited Result Codes that are returned automatically by the

MODEM to notify the occurrence of an event. For example the reception of a

SMS will force MODEM to return an unsolicited result code.

3.1.6.8 AT Commands Syntax

Case Sensitivity -

The AT commands are generally used in uppercase letters. However some

MODEMs and mobile phones allow both uppercase and small case letters.

Single Command -

The AT commands include a prefix AT which indicates the beginning of the

command to MODEM; and a carriage return which indicates the end of the

command.

Fig 3.12: AT Commands Syntax

However string AT itself is not the part of the command. For example in ATD,

D is the command name not ATD.

32


33/80

The extended AT commands have a + in the command name.

For example: AT+CGMI

Command Line -

Multiple AT commands can be sent to MODEM in a single command line. The

commands in a line are separated by a semi-colon (;).

For example: AT+CGMI; +CBS

String in Command Line -

Strings in a command line are enclosed in double quotes.

For example: AT+CGML=ALL

Information Response and Result Code

The Information Response and Result Codes, returned by the MODEM, have a

carriage return and line feed in the beginning as well as at the end.

For example:

33


34/80

OK

ERROR

Sequence of Execution -

In the command line, the command appearing first is executed first. The

execution then follows for second appeared command and so on. The execution

of commands in a command line takes place in sequential manner.

If an error occurs in the execution of a command, an error result code is returned

by the MODEM and the execution of the command line is terminated irrespective

of presence of other commands next in the command line.

Types of commands:

There are four types of AT commands:

1) Test commands2) Read commands

3) Set commands

4) Execution commands

For more details, see AT Commands.

Different Result Codes:

RESULT CODE DESCRIPTION

OK Successful Execution of a command

ERROR Execution of a command failed

+CMS ERROR Message service failure, is returned with an error code

Unsolicited Result Codes

+CDS Notify receipt of SMS status report of a new message tocomputer

34


35/80

+CDSI Notify receipt of SMS status report of a new message and its

location in memory to computer

+CMT Notify forwarding of a new SMS to computer

+CMTI Notify receipt of SMS status report of a new message and its

location in memory to computer

Fig 3.10 Commands used in GSM

3.1.6.9 Interfacing MODEM/Mobile phone with Windows platform

The Windows (XP and lower versions) comes with an application called

HyperTerminal for data communication through serial port of the computer. The

interfacing of the GSM/GPRS module with the serial port of the computer

involves following steps:

1) Connect RS-232 port of GSM module with the serial port of the computer.

Insert a SIM card in the module.

2) Open HyperTerminal from Start -> All Programs -> Accessories ->

Communications -> HyperTerminal.

3) Enter a name for the connection and press OK.

4) Now select the communication port (COM) at which GSM module is

connected.

5) Create a new connection set on HyperTerminal. Set parameters, like baud

rate as 9600, handshaking mode as none, parity bit as none, stop bit as 1 and data

bit as 8.

3.1.7 MAX 232:

35
http://www.engineersgarage.com/tutorials/at-commands


36/80

Max232 IC is a specialized circuit which makes standard voltages as

required by RS232 standards. This IC provides best noise rejection and very

reliable against discharges and short circuits. MAX232 IC chips are commonly

referred to as line drivers.

To ensure data transfer between PC and microcontroller, the baud rate and

voltage levels of Microcontroller and PC should be the same. The voltage levels

of microcontroller are logic1 and logic 0 i.e., logic 1 is +5V and logic 0 is 0V.

But for PC, RS232 voltage levels are considered and they are: logic 1 is taken as

-3V to -25V and logic 0 as +3V to +25V. So, in order to equal these voltage

levels, MAX232 IC is used. Thus this IC converts RS232 voltage levels to

microcontroller voltage levels and vice versa.

3.1.7.1 Pin Configuration:

Fig 3.9: Pin diagram of MAX 232 IC

36


37/80

3.1.8 RS 232(Female Port)

RS-232 is the component which is used to connect system (pc) to

microcontroller.

RS-232 (Recommended Standard 232) is the traditional name for a series

of standards for serial binary single-ended data and control signals connecting

between a DTE (Data Terminal Equipment) and a DCE (Data Circuit-

terminating Equipment). It is commonly used in computer serial ports. The

standard defines the electrical characteristics and timing of signals, the meaning

of signals, and the physical size and pin out of connectors.

RS232 is limited to point-to-point connections between PC serial ports and

devices. RS 232 hardware can be used for serial communication up to distances

of 50 feet.

3.1.8.1 Voltage levels:

The RS-232 standard defines the voltage levels that correspond to logical

one and logical zero levels for the data transmission and the control signal lines.For data transmission lines (TxD, RxD and their secondary channel

equivalents) logic one is defined as a negative voltage, the signal condition is

called marking, and has the functional significance. Logic zero is positive and the

signal condition is termed spacing.

Table 3.4: indicating voltage levels for DB 9 connector

Logic level Voltage level

1 -10V

0 10V

37


38/80

3.1.8.2 PIN CONFIGURATION

Fig 3.10: DB9 Connector with pin out

3.1.8.3 DB9 INTERFACING WITH MICROCONTROLLER USING MAX

232:

Fig 3.11:DB9 interfacing with microcontroller using MAX 232

3.1.9 Serial port connector:

The microcontroller is connected to the pc via a serial communication

port. The serial communication port is a combination of a female port and a male

38


39/80

port. The male port is connected to the DB-9 connector connected to the

microcontroller while the female port is connected to the serial port of the pc.

Fig 3.12: serial port connector

3.1.10 Resistors:

A resistor is a two-terminal passive electronic component that implements

electrical resistance as a circuit element. When a voltage V is applied across the

terminals of a resistor, a current I will flow through the resistor in direct

proportion to that voltage. This constant of proportionality is called conductance,

G. The reciprocal of the conductance is known as the resistance R, since, with a

given voltage V, a larger value of R further "resists" the flow of current I as givenby Ohm's law:

Fig 3.19: Resistors

39


40/80

Practical resistors can be made of various compounds and films, as well as

resistance wire (wire made of a high-resistivity alloy, such as nickel-chrome).

Resistors are also implemented within integrated circuits, particularly analog

devices, and can also be integrated into hybrid and printed circuits.

3.1.11 Capacitors:

A capacitor (formerly known as condenser) is a device for storing electric

charge. Capacitors used as parts of electrical systems, for example, consist of

metal foils separated by a layer of insulating film.

A capacitor is a passive electronic component consisting of a pair of

conductors separated by a dielectric (insulator). When there is a potential

difference (voltage) across the conductors, a static electric field develops across

the dielectric, causing positive charge to collect on one plate and negative charge

on the other plate. Energy is stored in the electrostatic field. An ideal capacitor is

characterized by a single constant value, capacitance, measured in farads. This is

the ratio of the electric charge on each conductor to the potential difference

between them.

Fig 3.20: Capacitors

Capacitors are widely used in electronic circuits for blocking direct current

while allowing alternating current to pass, in filter networks, for smoothing the

40


41/80

output of power supplies, in the resonant circuits that tune radios to particular

frequencies and for many other purposes.

C = Q/V

3.1.12 Crystal oscillator:

A crystal oscillator is an electronic oscillator circuit that uses the

mechanical resonance of a vibrating crystal of piezoelectric material to create an

electrical signal with a very precise frequency. This frequency is commonly used

to keep track of time (as in quartz wristwatches), to provide a stable clock signal

for digital integrated circuits, and to stabilize frequencies for radio transmitters

and receivers. Most common type of piezoelectric resonator used is the Quartz

Crystal, so oscillator circuits designed around them became known as "Crystal

Oscillators."

Fig 3.21: Crystal Oscillator

Quartz crystals are manufactured for frequencies from a few tens of

kilohertz to tens of megahertz. More than two billion (2109) crystals are

manufactured annually. Most are used for consumer devices such as

wristwatches, clocks, radios, computers, and cell phones. Quartz crystals are also

found inside test and measurement equipment, such as counters, signal

generators, and oscilloscopes.

3.1.13 Power supply:

41


42/80

In Power supply section, we use Step down transformer that steps down

voltage from 220V to 0-12V. This supply is regulated by using 7805 which

converts it into 5V constant supply. Then we can use this +5V supply as Vcc

anywhere in our hardware.

Parts:

Transformer: It steps down 220V to 0-12V supply voltage.

Full Bridge Rectifier : With diodes we can convert input 0-12V AC

signal into DC signal. This circuit works as Rectifier.

Capacitors : Capacitors are used for removing AC ripples so that the

output will be purely DC.

IC 7805 : This IC converts fluctuating or non-accurate input supply to

Regulated and constant +5V.

Fig 3.22 : Power Supply

42


43/80

3.2 SOFTWARE DESIGN:

3.2.1 Liquid Crystal Display

3.2.1.1 Initializing the LCD

Before you using the LCD, the program must initialize and configure it.

This is accomplished by sending a number of initialization instructions to the

LCD.

The first instruction to send is the no of data for the LCD i.e., with an 8-

bit or 4-bit data bus. The other thing need to specify is display matrix; in theselected LCD it is a 5x7 dot character font. These two options are selected by

sending the command 38H to the LCD as a command. The command can give to

the LCD by invoking the pre defined function call cmnd with passing parameters

value of 38H, the syntax for the same can be given like cmnd (0x38).

3.2.1.2 Writing command to the Display

The function for commands to display on LCD is given below:

void cmnd (unsigned char value)

{

P0 = value;

Rs = 0;

Rw = 0;

En = 1;

delay(1);

en = 0;

}

43


44/80

We can call this function in the program like this:

cmnd(0x38);

cmnd(0x80);

cmnd(0xC0);

3.2.2 Flowchart for the Project

Fig 3.25 Flow chart of GSM based Wireless Home Automation

44


45/80

CHAPTER IV

IMPLEMENTATION

4.1 HARDWARE IMPLEMENTATION

4.1.1 Schematic of GSM based Wireless Home Automation System

Fig 4.1: Schematic of GSM based wireless home automation system

45


46/80

4.1.2 Connections of AT89S52

The pin configuration of AT89S52:-

Fig 4.2: Pin diagram of AT89S52

In this project the microcontroller is connected to MAX232, LCD, and GSM and

Devices to be controlled.

The connections of microcontroller are given briefly below:

The reset pin is connected to the 9 th pin (RST) of AT89S52, as it is used

for set reset the program.

While the 10pin is connected to the 12th pin of MAX232.

46


47/80

11th pin of controller is connected to the 11th pin of MAX232.

The crystal oscillator which gives a frequency of 11.0592 MHz for the

required Baud rate of 9600Hz to the microcontroller. This crystaloscillator is connected in between 18th (XALT 1) and 19th (XALT 2)

pins of AT89S52 controller.

The 20th pin of controller is Grounded.

The pins from 32nd to 39th (Port 0) are used for the connections for data

lines of LCD.

Address Latch Enable pin (30th pin) of controller is connected to the

ground hence no connections need not to be given to this pin.

External Access pin (31st pin) must be connected to high i.e. VCC.

4.1.3 Pin connections of LCD

The 1st and 2nd pins of JHD162A LCD are connected to Ground and

high voltage VCC respectively.

3rd pin of LCD is connected to the centre pin of the Potentiometer or

variable resistor so as to adjust the contrast of LCD.

The 4th (RS) and 6th (EN) pins are connected to 1st (P1.0) and 2nd (P1.1)

pins of the microcontroller respectively.

The 5th pin (R/W) pin is connected to Ground as we have to write data

on LCD.

The 7th to 14th pins are data pins and are connected to the 39 th (P0.0) to

32nd (P0.7) pins of the microcontroller respectively.

47


48/80

The 15th and 16th pins are used for backlight purpose. 15th pin is

connected to VCC and 16th pin to Ground.

Fig 4.3: Connection of LCD with AT89S52.

4.1.4 MAX232, DB9 AND GSM CONNECTION:

MAX232 and DB9 connector plays a key role in program dumping and

communication between project kits to the PC host.

48


49/80

Capacitor C10 of capacitance 1Uf is connected across 1 st and 3rd pins of

MAX232 and C9 of capacitance 1Uf is connected in between 4 th and 5th

pins.

Charge pump capacitors are required for the MAX232 to work it as voltage

level shifter. The charge pump capacitors used here are C7 and C8 whose

capacitance is 1Uf. C7 is connected between 6th pin and ground, while C8

is connected across 2nd pin of MAX232 and Vcc.

12th and 11th pins of MAX232 are connected to the 10 th and 11th pins of

AT89S52 controller respectively. These acts as a transmitter and receiver

for the data flow.

To connect the MAX232 to the PC host we require a medium named as

DB9 connector. The 2nd and 3rd pin of the DB9 connector should be

connected to the 14th and 13th pins of MAX232 respectively. While the 5th

pin is grounded.

The GSM module is connected to the controller through the connections

between the DB9 connectors already mounted on the controller and GSM

modules.

49


50/80

CHAPTER-V

SOFTWARE IMPLEMENTATION

5.1 JHD162A LCD INTERFACING

5.1.1 Initializing the LCD

The first instruction to send is the number of data for the LCD i.e., with an

8-bit or 4-bit data bus. The other thing need to specify is display matrix; in the

selected LCD it is a 5x7 dot character font. These two options are selected by

sending the command 38H to the LCD as a command. The command can give to

the LCD by invoking the pre defined function call cmnd with passing parameters

value of 38H, the syntax for the same can be given like cmnd (0x38).

5.1.2 The initialization sequence code can be given as follows:

cmnd (0x38); // 2 lines and 5x7 matrix

cmnd (0x01); // display on, cursor blinking

cmnd (0x0E); //clear display screen

cmnd (0x80); // force cursor to begging of 1st line

5.1.3 Displaying the data into the LCD

50


51/80

void show(unsigned char value)

{

P0 = value;

Rs = 1;

Rw = 0;

En = 1;

delay(1);

en = 0;

}

5.1.4 Reading data to LCD

void string(unsigned char *s)

{

While(*s != \0)

{

show(*s);

s++;

}

}

To use this function in main() is as follows:

void main()

{

cmnd(0x80);

string(System Instaling);

}

51


52/80

CHAPTER VI

DEBUGGING TECHNIQUES

6.1 Keil vision Debugger

6.1.1 Introduction to Keil IDE

Keil is a compiler that has 3 windows, project window, edit

window, and build or command window Schematic. Today, Keil Software

provides a broad range of development tools for the embedded systems

marketplace. Their products include ANSIC compilers, macro assemblers,

debuggers, linkers, library managers, and real-time operating systems.

. It was then that Keil Software implemented the first C compiler designed

from the ground-up specifically for the 89C51 microcontroller.

6.1.2 Features

1. Nine basic data types, including 32-bit IEEE floating-point.

2. Flexible variable allocation with bit, data, bdata, idata, xdata, and pdata

memory types.

3. Interrupt functions may be written in C.

4. Full use of the 8051 registers banks.

5. Complete symbol and type information for source-level debugging.

6. Bit-addressable data objects.

7. Built-in interface for the RTX51 real-time kernel.

8. Support for dual data pointers on Atmel, AMD, Cypress, Dallas

semiconductor, Infineon, Philips, and Transcend microcontrollers.

9. Support for Phillips 8xC510,8xC71,and 8xC752 limited instructionsets.

52


53/80

The Keil 8051 Development Tools are designed to solve the complex

problems facing embedded software developers.

When starting a new project, simply select the microcontroller you use from

the Device Database and the vision IDE sets all compiler, assembler, linker,

and memory options for you.

Numerous example programs are included to help you get started with most

popular embedded 8051 devices.

The Keil Vision Debugger accurately simulates on-chip peripherals (CAN,

UART, SPI, Interrupts, I/O Ports, A/D Convertor, D/A convertor, and PWM

Modules) of your 8051 device. Simulation helps you understand hardware

configurations and avoids time wasted on setup problems. Additionally, with

simulation, you can write and test applications before target hardware is

available.

When you are ready to begin testing your software application with target

hardware, use the MON51, MONADI, or FlashMON51 Target Monitors, the

ISD51 In-system Debugger, or the ULINK USB-JTAG Adapter to download

and test program code on your target system.

6.1.3 Steps to follow while writing a program in keil:

1.Install Keil Micro Vision in your PC, Then after Click on that Keil Visionicon. After opening the window go to toolbar and select Project Tab then close

previous project.

2. Next select New Project from Project Tab.

3. Then it will open Create New Project window. Select the path where you

want to save project and edit project name.

53


54/80

4. Next it opens Select Device for Target window, it shows list of companies

and here you can select the device manufacturer company.

5. For an example, for your project purpose you can select the chip as

89c51rd2xx from Philips Group. Next Click OK Button, it appears empty

window here you can observe left side a small window i.e., Project Window.

Next create a new file.

6. From the Main tool bar Menu select File Tab and go to New, then it will

open a window, there you can edit the program.

7. Here you can edit the program as which language will you prefer either

Assembly or C.

8. After editing the program save the file with extension as .c or .asm, if you

write a program in Assembly Language save as .asm or if you write a

program in C Language save as .c in the selected path.

9. Then after saving the file, compile the program. For compilation go to project

window select source group and right click on that and go to Add files to

Group.

10. Here it will ask which file has to add. For an example here you can add

test.c as you saved before

11. After adding the file, again go to Project Window and right click on your c

file then select Build target for compilation. If there is any Errors or

Warnings in your program you can check in Output Window that is shown

bottom of the Keil window.

12. Here in this step you can observe the output window for errors and warnings

13. If you make any mistake in your program you can check in this slide for

which error and where the error is by clicking on that error

54


55/80

14. After compilation then next go to Debug Session. In Tool Bar menu, go to

Debug tab and select Start/Stop Debug Session.

15. Write a program for LEDs Blinking. LEDs are connected to PORT-1. You

can observe the output in that port.

16. To see the Ports and other Peripheral Features go to main toolbar menu and

select peripherals.

17. In this slide see the selected port i.e., PORT-1.

18. Start to trace the program in sequence manner i.e., step by step execution and

observe the output in port window

19. After completion of Debug Session Create a .Hex file for Burning the

Processor. Here to create a Hex file goes to project window and right click on

Target next select Option for Target.

20. It appears one window; here in target tab modify the crystal frequency as

you connected to your microcontroller.

21. Next go to Output tab. In that Output tab click on Create HEX File and

then click OK.

22. Finally Once again compile your program. The Created Hex File will appear

in your path folder.

55


56/80

APPENDICES

KEIL MICRO VISION IDE

Keil is a compiler that has 3 windows, project window, edit window, and build or

command window Schematic. Today, Keil Software provides a broad range of

development tools for the embedded systems marketplace. Their products include

ANSIC compilers, macro assemblers, debuggers, linkers, library managers, and

real-time operating systems.

Steps to follow while writing a program in keil:

1. Click on the Keil Vision Icon on Desktop.

2. The following figure will appear.

3. Click on the Project menu from the title bar.

4. Then Click on New Project.

56


57/80

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

your own folder.

6. Then Click on Save button above.

7. Select the component for your project. i.e. Atmel

8. Click on the + Symbol beside of Atmel.

57


58/80

9. Select AT89S52 as shown below.

10. Then Click on OK.

11. The Following figure will appear.

58


59/80

12. Then Click either YES or NOmostly YES.

13. Now your project is ready to USE.

14. Now double click on the Target1, you would get another option Source

group 1 as shown in next page.

15. Click on the file option from menu bar and select new.

59


60/80

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 EMBEDDED C or ASM.

60


61/80

18. For a program written in Assembly, then save it with extension . asm

and for EMBEDDED C based program save it with extension .C

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

Source.

61


62/80

20. Now you will get another window, on which by default EMBEDDED

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

port as shown in figure below.

62


63/80

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

26. Now keep Pressing function key F11 slowly and observe.

27. You are running your program successfully.

63


64/80

SETUP OF HYPERTERMINAL

Go to:

1. Start Menu>> Programs >> Accessories >> Communications >> Hyper

Terminal

After that HyperTerminal window will open. If it prompt for checking of default

program as shown in fig, then say yes to it.

2. Click Yes

3. Type Connection Name as 8051 (or as per your Choice)

64


65/80

4. Select COM PORT (1, 2, 3 etc) whichever is available. (NOTE: Very Less

USB- TO Serial Converters as Reliable)

So use Standard Serial Port

65


66/80

5. Do Port Setting as Given Below.

66


67/80

Then Click Apply and OK.

6. Now you See Bottom Left side It shows Connected.

7. Now burn the Hex File (Given) and Switch on the Circuit after Connecting

Specified Serial Port .You will see output as Follows:

67


68/80

If everything works fine you will see Hello World on the screen. Otherwise check

your setup.

68


69/80

GSM BASED HOME AUTOMATION SYSTEM

/* Program used for Home automation */

#include

sbit rs = P1^0;

sbit e = P1^1;

sbit Green = P2^0;

sbit Blue = P2^1;

sbit Yellow = P2^2;

sbit Red = P2^3;

void delay(int time)

{

int i, j;for(i = 0; i > time; i++)

for(j = 0; j < 1275; j++);

}

void cmnd(unsigned char g)

{

P0 = g;

rs = 0;

e = 1;

delay(1);

e = 0;

}

void show (unsigned char g)

69


70/80

{

P0 = g;

rs = 0;

e = 1;

delay(1);

e = 0;

}

void init ()

{

cmnd (0x38);

cmnd (0x01);

cmnd (0x0C);

cmnd (0x80);

}

void string (unsigned char *s)

{

while (*s != '\0')

{

show (*s);

s++;

}

}

void serial_init()

{

TMOD = 0x20;

SCON = 0x50;

TH1 = 0xFD;

70


71/80

TL1 = 0xFD;

TR1 = 1;

}

void sendbyte(unsigned char y)

{

SBUF = y;

while(TI == 0);

TI = 0;

}

void receivebyte()

{

unsigned char c;

while(RI == 0);

RI = 0;

c = SBUF;

}

void sendstring(unsigned char *str)

{

while(*str != '\0')

{

sendbyte(*str++);

}

}

void Getline();

void Send_sms();

char Gps;

71


72/80

unsigned char Num[10];

unsigned char Disp[16];

unsigned char Inmsg[100];

void main()

{

P2 = 0xFF; //switch off all loads

init();

serial_init();

string(SYSTEM INSTALING);

init();

string("Initializing");

cmnd(0xC0);

string("Modem plz wait..");

delay(50);

sendstring("AT");

cmnd(0x01);

string("AT OK");

delay(50);

sendstring("ATE0");

cmnd(0x01);

string("ECHO OK");

delay(50);

sendstring("AT+CREG?");

delay(50);

sendstring("AT+CNMI=2,0,2,0,0");

72


73/80

cmnd(0x01);

string("PHASE OK");

delay(50);

sendstring("AT+CMGF=1");

cmnd(0x01);

string("TEXT OK"); //change to Text mode

delay(50);

sendstring("AT+CMGD=1,4");

delay(50); //Delete all sms

cmnd(0x01);

string("Waiting for SMS.");

while(1)

{

sendstring("AT+CMGR=1"); //Read for message

Getline();

if (!Inmsg) //got new message

{

Num = ",";

Gps = Instr(Inmsg , Num);

Gps = Gps + 5;

Num = Mid(Inmsg , Gps , 10); //extract the sender number

Getline(); //get the message

Inmsg = Lcase(inmsg);

cmnd(0x01);

string("1 Msg Received");

cmnd(0xC0);

73


74/80

string("from:");

cmnd(0xC5);

string(Num);

delay(50);

if (Inmsg = "Green on")

{

Green = 0;

Inmsg = "Green LED ON";

cmnd(0x01);

string(Inmsg);

Send_sms();

}

else if (Inmsg = "Green off")

{

Green = 1;

Inmsg = "Green LED OFF";

cmnd(0x01);

string(Inmsg);

Send_sms();

}

else if (Inmsg = "Blue on")

{

Blue = 0;

Inmsg = "Blue LED ON";

cmnd(0x01);

string(Inmsg);

74


75/80

Send_sms();

}

else if (Inmsg = "Blue off")

{

Blue = 1;

Inmsg = "Blue LED OFF";

cmnd(0x01);

string(Inmsg);

Send_sms();

}

else if (Inmsg = "Yellow on")

{

Yellow = 0;

Inmsg = "Yellow LED ON";

cmnd(0x01);

string(Inmsg);

Send_sms();

}

else if (Inmsg = "Yellow off")

{

Yellow = 1;

Inmsg = "Yellow LED OFF";

cmnd(0x01);

string(Inmsg);

Send_sms();

}

else if (Inmsg = "Red on")

75


76/80

{

Red = 0;

Inmsg = "Red LED ON";

cmnd(0x01);

string(Inmsg);

Send_sms();

}

else if (Inmsg = "Red off")

{

Red = 1;

Inmsg = "Red LED OFF";

cmnd(0x01);

string(Inmsg);

Send_sms();

}

else

{

Inmsg = "Invalid Command";

cmnd(0x01);

string(Inmsg);

Send_sms();

}

}

delay(25);

sendstring("AT+CMGD=1,4"); //delete all sms

delay(50);

76


77/80

cmnd(0x01);

string("Waiting for SMS.");

delay(50);

}

}

void Send_sms()

{

If (Num != "")

{

sendstring("AT+CMGS="); //send sms

delay(50);

sendstring(Inmsg);

delay(50);

}

}

void Getline()

{

Inmsg = "";

while(1)

{

Gps = Inkey()

If (Gps > 0)

{

switch(Gps)

{

Case 13 : If (Inmsg != "")

break;

77


78/80

Case 10 : If (Inmsg != "")

break;

Case else

Inmsg = Inmsg + Chr(gps);

}

}

}

}

78


79/80

REFERENCES

Muhammad Ali Mazidi, 8051 micro controller and embedded systems, PHI

Prentice hall India, Eastern Economy Edition, www.phindia.com.

U.S. Shah, 8051Microcontroller and Embedded Systems.

www.8051projects.info

www.8051projects.net

www.openstudy.com

www.engineersgarage.com

Wikipedia : http://en.wikipedia.org

www.google.co.in

Special Thanks to Mr. Narinder Kumar (Embex Technologies), Mr. Vinay

Rathi (ZCC Networking Solution) and Ms. Vasu Nahoria (Infowiz) for their

tremendous support and reference.

79


80/80
http://www.phindia.com/http://www.8051projects.info/http://www.8051projects.net/http://www.openstudy.com/http://www.engineersgarage.com/http://en.wikipedia.org/wiki/Levelshttp://www.google.co.in/

final report home automation - all

Documents