Trying to build a small GSM library

Hi,

About the console.log - it won't hurt to use it when running off a battery - you just won't see anything. I guess you could define a function like:

function log(type, message) {
  if (type=="good") digitalWrite(LED2,1); // green
  if (type=="bad") digitalWrite(LED1,1); // red
  console.log(">"+message);
}

log("good", "It worked!");
log("", "It's ok...");
log("bad", "It's smoking");

You could also try calling a callback for the response message, rather than using intervals...

I've added a timeout so it won't just break if something goes wrong, but I'm not handling it very well at the moment :)

var cmd="";
var responseText = "OK";
var responseCallback = undefined;
 
//Function handles data coming in from Serial.
Serial4.on('data',function (data) {
  cmd+=data;
  // maybe we should be looking for newline instead?
  if(cmd.indexOf(responseText) > 0){
    console.log(cmd);
    if (responseCallback) responseCallback();
    responseCallback = undefined;
    cmd="";
  }
});
 
 
//Function handles sending AT commands to GSM device.
function Send_Command(command,response,time,caller){
  if (responseCallback) {
    console.log("we were already doing something!");
    return;
  }
  
  // if we didn't get anything within 'time' ms, 
  var timeout = setTimeout(function(){    
    console.log("Timeout for "+command);
    caller(false);
  },time);
  responseText = response;
  responseCallback = function() {
   // if we actually did want to repeatedly send the command, do it here
   clearInterval(timeout); // clear the timeout
   caller(true);
  };
  // send command
  Serial4.write(command);
}
 
 
//Start the GSM Module
function Start_GSM(callback) {
  console.log("GSM Starting...");
  pinMode(C0,"output");
  digitalPulse(C0,1,2000);
  // this will send the AT command right after C0 has raised.
  // Not sure it's what you want? setTimeout might be better here
  Send_Command("AT\r\n","OK",500,function() {
    console.log("GSM Started.");
    callback();
  });
}

//Send the text message
function Send_SMS(phoneNumber,message, callback){
 console.log("Setting SMS Mode..");
  Send_Command("AT+CMGF=1\r\n","OK",1000,function(){
    answer=">";
    console.log("Setting Phone Number.."); 
    Send_Command('AT+CMGS=\""+phoneNumber+"\"\r',">",1000,function(){
      console.log("Send Message"); 
      Send_Command(message+"\x1A\r","OK",3000,function() {
       console.log("Message Sent"); 
       callback();
      });
    });
  });
}

// You can then chain the callbacks together to use the library
Start_GSM(function() {
  Send_SMS("+441234567890","Hello There", function() {
     Send_SMS("+441234567890","Hello There Again", function() {
      Stop_GSM(function() {
         console.log("phew...");
      });
     });
   });
});