Receiving SMS using GSM and controlling LED using Arduino - arduino

Question

Has someone come up with a solution with the above stated problem?
We are using Arduino Duemilanove and SIM 900 GSM module (http://robokits.co.in/shop/index.php?main_page=product_info&products_id=303)
We've tried to work on the similar problem of lightning LEDs from port 9-12 when we send an sms #aibicidi, where i = 0 or 1, 0 =off, 1=on. E.g. #a1b1c1d1 will switch on all the LEDs.
When we upload the code and run it through serial monitor and enter the #a1b1c1d1 in the serial monitor, we can see all the LEDs lighten up. But if we send the sms with having content "#a1b1c1d1", we don't see any function of LEDs.
It would be great if anyone can give some guidance about the same.
char inchar; //Will hold the incoming character from the Serial Port.
int led1 = 9;
int led2 = 10;
int led3 = 11;
int led4 = 12;
void setup()
{
// prepare the digital output pins
pinMode(led1, OUTPUT);
pinMode(led2, OUTPUT);
pinMode(led3, OUTPUT);
pinMode(led4, OUTPUT);
digitalWrite(led1, LOW);
digitalWrite(led2, LOW);
digitalWrite(led3, LOW);
digitalWrite(led4, LOW);
//Initialize GSM module serial port for communication.
Serial.begin(9600);
delay(3000); // give time for GSM module to register on network etc.
Serial.println("AT+CMGF=1"); // set SMS mode to text
delay(200);
Serial.println("AT+CNMI=3,3,0,0"); // set module to send SMS data to serial out upon receipt
delay(200);
}
void loop()
{
//If #a1b1c1d1 comes as sms, all LEDs should light up.
if(Serial.available() >0)
{
inchar=Serial.read();
if (inchar=='#')
{
delay(10);
inchar=Serial.read();
//first led
if (inchar=='a')
{
delay(10);
inchar=Serial.read();
if (inchar=='0')
{
digitalWrite(led1, LOW);
}
else if (inchar=='1')
{
digitalWrite(led1, HIGH);
}
delay(10);
//Second led
inchar=Serial.read();
if (inchar=='b')
{
inchar=Serial.read();
if (inchar=='0')
{
digitalWrite(led2, LOW);
}
else if (inchar=='1')
{
digitalWrite(led2, HIGH);
}
delay(10);
// Third led
inchar=Serial.read();
if (inchar=='c')
{
inchar=Serial.read();
if (inchar=='0')
{
digitalWrite(led3, LOW);
}
else if (inchar=='1')
{
digitalWrite(led3, HIGH);
}
delay(10);
//Fourth led
inchar=Serial.read();
if (inchar=='d')
{
delay(10);
inchar=Serial.read();
if (inchar=='0')
{
digitalWrite(led4, LOW);
}
else if (inchar=='1')
{
digitalWrite(led4, HIGH);
}
delay(10);
}
}
Serial.println("AT+CMGD=1,4"); // delete all SMS
}
}
}
}
}

Answer 1

First do not use delay
Serial.begin(9600);
delay(3000); // give time for GSM module to register on network etc.
This is neither necessary nor reliable. Instead of waiting some random time, you can check the network status with AT+CFUN and/or AT+COPS. If the GSM module is already attached to a network when you open the serial connection, it is a waste of time waiting like that. And if is not attached you should wait explicitly for that to happen (polling CFUN/COPS or enabling AT+CREG), otherwise you risk waiting too short time. See the 27.007 specification for more information for those commands.
Second do not use delay
Serial.println("AT+CMGF=1"); // set SMS mode to text
delay(200);
Please do not write code like this. See this answer on why using delay is such a bad idea, and this answer for suggestion to how to handle properly.