In this project we will make project on Electricity problem. Today there is big problem of electricity for the farmers , because electricity board supplu it with interval of two hours in rural areas. So farners don’t know when it will come and they are helpless to switch on motors. In this project we will make GSM Modem based alert system which will help us when electricity will be coming. Farmer can switch on off electric motor with mobile function.
Whole Project is divided in to three parts
1. Electricity Detection Circuit
2. Electricity available Alert with GSM modem
3. Electricity Control.
. Because this GSM system helps us to send the messages to mobiles we will send sms on particular nos. when any problem increases above the peak level.We will use AT commands to send sms from mobile.
VARIOUS STEPS OF PROJECT:
1) POWER SUPPLY +5V
2) MICROCONTROLLER AT89S52
3) MAX232 CIRCUIT
4) GSM MODEM
Pin no 40 is connected to the positive supply. In this project we provide a 5 volt dc power supply. This power supply is truly regulated power supply. Pin no 20 is connected to the negative supply. Here we supply a negative voltage on this pin. Crystal is connected to the pin no 18 and 19 of the microcontroller. Crystal provide a clock signal to run the vehicle and process all the internal requirement of the circuit.. For the regulated power supply we use ic 7805 as a regulator to provide a fix 5 volt power supply.
We will use GSM modem sm300 at 9600 baud rate.
This GSM modem is a highly flexible plug and play quad band GSM modem for direct and easy
integration to RS232. Supports features like Voice, Data/Fax, SMS,GPRS and integrated TCP/IP
Specifications for Fax
· Group 3, class 1
Specifications for data
· GPRS class 10: max 85.6 kbps(downlink)
· PBCCH support
· Coding schemes CS 1,2,3,4
· CSD upto 14.4 kbps
· Non transparent mode
· Quad Band GSM/GPRS
· GPRS multi-slot class 10/8
· GPRS Mobile station class B
· Compliant to GSM Phase 2/2+
o Class 4 (2W@850/900Mhz)
o Class 1(1W@1800/1900Mhz)
· Control via AT commands(GSM 07.07,
07.05 and enhanced AT commands)
· Operation Temperature(-20 deg C to
+55 deg C)
Specifications for SMS
· Point-to-point MO and MT
· SMS cell broadcast
· Text and PDU mode
· Use AC – DC Power Adaptor with following ratings
· DC Voltage : 12V
· DC Current : 1A
· Polarity : Centre +ve & Outside –ve
· Current Consumption in normal operation 250mA, can rise up to 1Amp while transmission.
· RS-232 through D-TYPE 9 pin connector, Serial port baud rate adjustable 1200 to115200
bps (9600 default)
· Stereo connector for MIC & SPK
· Power supply through DC socket
· SMA antenna connector
· Push switch type SIM holder
· LED status of GSM / GPRS module
· Insert SIM card: Press the yellow pin to remove the tray from the SIM cardholder. After
properly fixing the SIM card in the tray, insert the tray in the slot provided.
· Connect Antenna: Screw the RF antenna on the RF cable output provided.
· If voice call is needed, connect the mic and speaker to stereo sockets.
· Connect RS232 Cable: (Cable provided for RS232 communication) Default baud rate is
9600 with 8-N-1, no hardware handshaking. Cable provided has pins 7 and 8 shorted that will
set to no hardware handshaking. In you need hardware handshaking the pins 7-8 can be
taken for signaling.
o Pin 2 is RS232 level TX out
o Pin 3 is RS232 level RX in
o Pin 5 is Ground
o Pin 7 RTS in (shorted to pin 8 in cable for no hardware handshaking)
o Pin 8 CTS out (shorted to pin 7 in cable for no hardware handshaking)
Connect the power Supply (9-12V) to the power jack. Polarity should be Center +ve and
outer –ve DC jack.
Network Led indicating various status of GSM module eg. Power on, network registration &
After the Modem registers the network, led will blink in step of 3 seconds. At this stage you
can start using Modem for your application.
Examples for send and receive SMS
For sending SMS in text Mode:
AT+CMGF=1 press enter
AT+CMGS=”mobile number” press enter
Once The AT commands is given’ >’ prompt will be displayed on the screen.
Type the message to sent via SMS. After this, press ctrl+Z to send the SMS.
If the SMS sending is successful, “ok” will be displayed along with the message number.
For reading SMS in the text mode:
AT+CMGF=1 Press enter
Number (no.) is the message index number stored in the sim card. For new SMS, URC will be received
on the screen as +CMTI: SM ‘no’. Use this number in the AT+CMGR number to read the message.