GSM INTERFACING WITH PIC 16F877A

GSM INTERFACING  WITH PIC 16F877A:

• SIM300 GSM Modem is able to take any GSM network operator SIM card and behave just like a mobile phone with its own unique phone number.

• The RS232 interface lets modem to communicate with RS232 port of PC or compatible embedded system circuitry.

• Implementation of SMS controlled devices, Auto reply; remote control is possible via SIM300.

• The modem can be directly interfaced with microcontroller. It can be used to send, receive and process SMS/ call

• GPRS facility brings internet and FTP connection to your embedded project.

Popular Applications

• SMS based Remote Control Systems
• Security Applications and Sensor Monitoring
• GPRS/ TFTP Mode Remote Data Logging

Features

• Reliable for 24×7 operations
• Status of Modem Indicated by LED
• Easy to Use and cheap Cost
• Quad Band Modem supports all GSM operator SIM cards

Operation of SIM300 GSM Module

• There are three pins namely GND, RX and TX can be seen in SIM300 GSM modem.

• Where GND as reference and RX and TX are the pins to receive and transmit serial data for a bit rate 9600.

• To control GSM modem we send AT commands serially to GSM modem, you can use terminal (Putty) to test GSM modem is working or not.

Testing GSM Modem SIM300 with PC

• Power the GSM modem, power LED will be ON. Then network LED keeps ON state until status LED turned ON and blinks at faster rate. (Searching for the network if you didn’t insert the SIM card)

• Once it catches the network, the status LED blinking rate reduces accordingly.

• Power on GSM modem with SIM card and connect to PC via RS232 serial interface, here I am using USB to serial converter, because my laptop .Lhas to serial port..

• Open putty and enter AT commands and press enter,

SIM300 AT commands

AT commands send SMS
Set format to Text: AT+CMGF=1
Receiver number: AT+CMGS=9495XXXXXX
Then type message
Cntrl+z

AT commands for call= ATD9495XXXXXX;
AT commands to disconnect call= ATH

More AT Commands can be seen here SIM300 AT Commands

Interfacing GSM Module with PIC16F28A

• We have used two push buttons one to send message and another to make call; also there are three LEDs GREEN, YELLOW and RED.

GREEN=System ready to make call and SMS
YELLOW= Call
RED= Message

• We have defined two user defined program send_sms(); and call(); under these programs we specified AT commands for sending SMS and call respectively.

• After green LED in ON, press the call button to make call, this will direct the program to a user defined program call(); then you can see calling to a number that you pre-programmed.

• By pressing message button, program will call a user defined function send_sms(); you will receive text message to the number that you programmed.

Testing:

Project Objective:

To complete the project we should follow some steps
1)      Test the simple AT Command.
2)      Connect a call to a GSM mobile number (Dial a number).
3)      Send a text message to a mobile number
Now question is how we test AT command?
You can easily test it on windows Hyperterminal software. See bellow picture how it look like.
 

Project Objective:

To complete the project we should follow some steps
1)      Test the simple AT Command.
2)      Connect a call to a GSM mobile number (Dial a number).
3)      Send a text message to a mobile number
Now question is how we test AT command?
You can easily test it on windows Hyperterminal software. See bellow picture how it look like.
 

AT Command:

AT+CMGF Message Format : This command is used to select SMS protocol data unit (PDU) mode or SMS Text mode.
AT+CSCS Select TE character set : This command informs the data card of which character set is used by the TE. The data card is then able to convert character strings correctly between TE and ME character sets.
AT+CMGS Send Message : Sends a message from a TE to the network (SMS-SUBMIT). The message reference value <mr> is returned to the TE on successful message delivery. Sending can be cancelled with the <ESC> character. <ctrl-Z> must be used to indicate the ending of the message body.

Circuit Diagram:

Bellow you will see the Circuit Diagram of interfacing GSM module with pic microcontroller

Circuit Diagram:

Bellow you will see the Circuit Diagram of interfacing GSM module with pic microcontroller