Receive Message with Arduino with ordinary GSM module (no GSM shield) with AT commands

Recently I found many people asking queries about using an ordinary GSM module with Arduino. Like, is it possible to use a GSM module locally available instead of Arduino GSM Shield.. Answer is .Yes ! it is possible..


Steps to that ..

1.  Find your GSM modules Baud rate
2. Connecting to Arduino .. You need to connect only 3 pins from GSM to Arduino
        *  RX from Arduino to TX of GSM
        *  TX from Arduino to RX of GSM module
        *  GND pin from GSM to GND of Arduino..

MAKE SURE THAT U HAVE CONNECTED ALL PINS CORRECTLY !!

If yes ! .. your hardware interfacing is Over .. !

Now , about the Arduino program. We have a library already in Arduino called GSM.h .
Here , we are not using that because we are not using GSM shield so there is a chance of error..
This method is simple though . we use simple "Serial" function and "String"  function.

Program for receiving a message ..follows ..
////////////////////////////////////////////////////////////////////////////////////////////

String inchar;

void setup()

{

Serial.begin(9600);

Serial.println("Message receiver Testing");

Serial.println("AT\r");

delay(1000);                 

Serial.println("AT+CMGF=1\r");   

delay(1000);

Serial.println("AT+CNMI=1,2,0,0\r");

}

void loop()

{

while (Serial.available())

{

 inchar = Serial.readString();

Serial.println(inchar);

}

}

////////////////////////////////////////////////////////////////////////////////////////////////

LOGIC OF program 

* Declare "inchar" as string for receving the message 

* In setup() set your GSM for incoming message mode

* AT commands are used for this . (not going detail in to AT commands )

* In loop() , if a data is available from serial port, it will be saved to "inchar" 

* "inchar" is displayed using Serial.println command

/////////////////////////////////////////////////////////////////////////////////////////////////////
another code for the same ..

void SMS_Read();

String inchar;

void setup()

{

Serial.begin(9600);

Serial.println("Message receiver Testing");

Serial.println("AT\r");

delay(1000);                 

Serial.println("AT+CMGF=1\r");   

delay(1000);

Serial.println("AT+CNMI=1,2,0,0\r");

}

void loop()

{

while (Serial.available())

{

 inchar = Serial.readString();

if(inhar.indexOf("+CMTI:") >=0)

{

SMS_Read();

}

}
}

void SMS_Read()

{

delay(500);

Serial.println("AT+CMGR=1\r");

delay(5000);

return;

}

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
and if you want to turn on an LED by sending and sms "ledON" ...try this..

While receiving an sms you will get details like date, time, sms, sms sender number etc...you can check this in the serial terminal .. so what we need to do is to check whether the incoming data has got the required data.. 
for example if you want to turn on an led by sendin sms "ledON" ... try this program code


void SMS_Read();
String inchar;
void setup()
{
pinMode(ledPin1,OUTPUT);
Serial.begin(9600);
delay(10)
;Serial.println("AT\r");   
delay(1000);                  
Serial.println("AT+CMGF=1\r");    
delay(1000);

Serial.println("AT+CNMI=1,2,0,0\r");
}
void loop()
{
while (Serial.available())
{
 delay(3); 
 d = Serial.readString();
 if(d.indexOf("ledON") >=0)
   {
  digitalWrite(ledPin1,HIGH); 
  Serial.println("light one is ON");
    }
if(d.indexOf("+CMTI:") >=0)
{
SMS_Read();

}
}
void SMS_Read()
{
delay(500);
Serial.println("AT+CMGR=1\r");
delay(5000);
return;

}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

These two programs worked for me in Arduino UNO .. Hope you will find this helpful :) 

Queries accepted ..willing to help if your problem is inside my range of knowledge :)