sim900A gsm module and programming

SIM900A GSM/GPRS Module

SIM900 is an ultra-compact and reliable wireless SMT (Surface Mount Technology) type quad-band GSM/GPRS module. It is very compact in size and easy to use as plug in GSM Modem. The Modem is designed with 3V3/5V TTL interfacing circuitry, which allows you to directly interface to 5V microcontrollers (PIC, Arduino, AVR etc) as well as 3V3 Microcontrollers (ARM, ARM Cortex XX, etc) .The baud rate can be configurable from9600-115200. AT commands are used to interface and control the GSM/GPRS module.

 Features of SIM900A are as follows:
RS 232/ Interface DB port
Voice communication port
On board voltage regulator
Power/single LED indication
SMA connector for antenna connection
The sim900 offers GSM/GPRS900/1800/1900 MHz for voice, SMS, DATA, Fax
Low cost
Module can be easily interfaced with AT commands

AT is the abbreviation of attention and AT commands are instructions used to control and interface the modem. Despite the fact that every command line starts with “AT”, it is not a part of the command name but is just the prefix informing the modem about the start of a command line. For example, D is the actual command name in ATD (Dial) and +CMGR is the actual command name in AT+CMGR (Read SMS Messages). Basically, there are two types of AT commands and they are basic commands and extended commands. The AT commands starting with “+” are extended commands and almost all of the GSM AT commands are extended commands. For example, +CMGR (Read SMS Messages), +CMGL (List SMS Messages) and +CMGS (Send SMS Messages) are extended commands. Similarly, the AT commands that do not start with the “+” are basic commands. For example, H (Hook Control), A (Answer), D (Dial) and O are basic commands.

Connection:- connect arduino pin9 to rx of gsm module..  connect pin 10 to tx..  common ground connection.. and insert the sim card into the sim slot

Example program:--

#include <SoftwareSerial.h>
SoftwareSerial mySerial(9, 10);
void setup(){  mySerial.begin(9600);   // Setting the baud rate of GSM Module    Serial.begin(9600);    // Setting the baud rate of Serial Monitor (Arduino)  delay(100);}

 void loop(){  mySerial.println("AT+CMGF=1");    //Sets the GSM Module in Text Mode  delay(1000);  // Delay of 1000 milli seconds or 1 second  mySerial.println("AT+CMGS=\"+91xxxxxxxxxxx\"\r"); // Replace x with mobile number  delay(1000);  mySerial.println("kishor here");// The SMS text you want to send  delay(100);  Serial.println("kishor here");   mySerial.println((char)26);// ASCII code of CTRL+Z  delay(1000);}