GSM SMS Based Home Appliance Control System

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GSM SMS Based Home Appliance Control System
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Project Cost:- INR Rs.5800/-   USD 195$   ( Courier Charges additional )

SMS Remote Control - GSM Remote

Designed for control application, this project provides 4 relay outputs. It can be used in various applications. Connection to the relay outputs is via “pluggable type” screw terminal blocks. The project presented here is based on world’s most powerful intel’s mcs-51 family of microcontroller atmel at89c51. In this project we are using AT 89C52 microcontroller.

The project can be used for switching on various appliances by sms from any mobile phone. The circuit is connected to gsm modem through RS232 cable to 9 pin D-shall connector connected on both sides. IC max 232 is a level converter ic to convert TTL level data to +12v and –12v level. For complete details on this IC, refer to manufacturer’s data sheet.

We used sim300 gsm modem which is readily available in the electronic market.

 

Circuit Description:

Port 3.0 is Rxd pin to receive data serially and port3.1 is Txd to transmit data serially.

Circuit is driven by 12V 1 AMP power supply connected to pcon1. Diodes D1-D4 forms bridge circuit.  C1 and C2 are filter capacitors. IC1 7805 is 5v regulator IC to give stablised supply to microcontroller.  LD5 LED is a power indication LED.

R18 is a current limiting resistor. Crystal gives the necessary clock to microcontroller.

All our relays are operated by 12v dc. Relay output can be connected to any 250v, 7 amp. load. Please don’t cross this limit other wise you will damage the relay circuit.

IC2 is atmel at 89C52 microcontroller. It has four ports. This controller has inbuilt uart (universal synchronous,asynchronous receiver transmitter, pin no 10 is Rx pin and pin number 11 is Tx pin of the uart. Through these two pins micro-controller is able to communicate with the gsm modem. Communication baud rate is 1200 bits per second.

Port 2 controlls all our relays. Output of this port is pulled high through pullup resistors sil arrays(single in line resistor array). Hence the output of pin nos 25 to 28 are by default high( at 5v logic), all relays stays off on power up. All the relay driver circuits are similar. We will explain one of them here .

Q1 to Q8 all are npn general purpose transistors. NPN transistor will become ON when base is high. If you refer circuit diagram Q1 base is driven by R2 connected to pin no 28 of the IC2. As this pin is at logic high , Q1 is on(conducting) and it’s collector remains at low logic(transistor acts as switch, very low resistance between emitter and collector),resulting base of the transistor is low and transistor Q2 is in off state(non-conducting). To switch on Q2, we have to switch off Q1. To switch off the Q1 the program inside the micro-controller must bring the logic at pin number 28 to low logic. Q1 will become off and Q2 base will get high logic through r3 and will become on. Relay coil of RL1 will get energised as the current will pass through coil , Q2 transistor collector and emitter to ground. Normally open contact will close the connection. Load should be connected to the out put of the contacts on CON1. Diode d5 connected across the relay coil is to protect the circuit from the induced emf generated by the relay coil during on/off operation. LD1 is relay1 on indication LED. R4 is a current limiting resistor. All the relay circuit works in the same manner.

IC3 max 232 IC is a level converter IC. IBM PC com port is designed for network which works on 12v dc where as our controller logic is at 5v. We need to convert this data to +12v &-12v logic before it is sent to PC. This IC has transreceiver level converter.

Transmitter part convert the TTL logic to com port logic and receiver part convert the signals coming from PC to TTL level before it is given to micro-controller. All the components connected around this IC is as per the application notes given in the datasheet by the manufacturer.

Capacitor c3 and r17 gives the required reset pulse to microcontroller. Crystal x1 along with capacitor c4 and c5 gives the required clock pulse to microcontroller.

Resistances R4, R8, R12, R16 connected to indication LEDs are current limiting resistors.

OPERATION

To switch on devices, You can send sms to the device as ON1 ON2 ON3 and so on. To switch off devices send sms as OFF1 OFF2 OFF3 and so on .

To check status of all the devices send  S.

To switch on or off devices and know the status send sms as ON1 OFF2 ON4  ON3 S.

 

Communication between SIM300 modem and microcontroller takes place via serial port using Sim300 AT command set. Which can be downloaded from the official SIMCOM site.

Some are given here, can be tried on PC using hyper terminal.

SMS commands

Set SMS system into text mode, as opposed to PDU mode.

AT+CMGF=1

OK

Send an SMS to myself.

AT+CMGS=”+9196xxxxxxxx”

> This is a test

+CMGS: 199

OK

Unsolicited notification of the SMS arriving

+CMTI: “SM”,2

Read SMS message that has just arrived.

Note: the number should be the same as

that given in the +CMTI notification.

AT+CMGR=23

+CMGR: “REC UNREAD”,”+9196xxxxxxxx”,,”12/11/01,15:45:24+22″

This is a test

OK

For any inquiry please contact at  joginderprojects@gmail.com

GSM SMS Based Home Appliance Control System, 4.3 out of 5 based on 25 ratings
3 Comments
  • gagandeep
    February 28, 2013
    #1
    VN:F [1.9.22_1171]
    Rating: 5.0/5 (1 vote cast)

    I want to buy this….. need more info.

  • swapnil
    October 23, 2013
    #2
    VN:F [1.9.22_1171]
    Rating: 3.5/5 (2 votes cast)

    sir how ur system know that sms is received

  • Hobby Projects Hobby Projects
    November 10, 2013
    #3
    VN:F [1.9.22_1171]
    Rating: 5.0/5 (1 vote cast)

    SMS is received by the modem and is detected by the programmed microcontroller

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