How to Turn On SIM900 with arduino.

We were getting some strange behavior out of the SIM900 module.
Some times the module was working ok, and others not so ok. :)

The main problem was in turning on method of the SIM900.

The solution:
Turn off and Then Turn on the SIM900.

The arduino code with the NewSoftSerial:


#define GSM_ON_PIN 8


int AvrHardwareHelper::TurnOffGsm()
{

mySerial.println("AT+CPOWD=1");

delay(3000);
digitalWrite(GSM_ON_PIN, LOW);
delay(2000);
digitalWrite(GSM_ON_PIN, HIGH);
delay(2500);

return atCommandResult;
}

int AvrHardwareHelper::TurnOnGsm(char* pin, int pinSize)
{
mySerial.println("AT+CFUN=1");
delay(600);
mySerial.flush();
mySerial.println("AT");
delay(600);

int numberOfBytesRead = 0;
while((mySerial.read()) > 0)
{
numberOfBytesRead++;
}

if(numberOfBytesRead==0)
{
digitalWrite(GSM_ON_PIN, HIGH);
delay(1200);
digitalWrite(GSM_ON_PIN, LOW);
delay(2500);
}

mySerial.flush();
delay(2000);

.... Do the rest here, at+cpin, etc....
}




pinMode(GSM_ON_PIN, OUTPUT); // sets pin 5 as output
mySerial.begin(9600);
TurnOffGsm();
TurnOnGsm("1234", 4);


This is the main difference with all the samples on the web.
If someone is searching for more info, please just leave a comment.