Have working code. SMS would initally send, but now it doesn't.

Official Hardware Retired GSM Shield
1

Hello,

I am working on a school project that involves using the arduino to send sms messages via a gsm module. I am currently using a SIM900 board with its set of libraries (http://wiki.iteadstudio.com/SIM900/SIM900A_GSM/GPRS_Minimum_System_Module). This is the code I happened to get working:

#include "SIM900.h" //libraries included for module to work

#include <SoftwareSerial.h>

#include "sms.h"

SMSGSM sms;
boolean started=false; //sets initial condition for gsm module
void setup()
{
Serial.begin(9600);
Serial.println("GSM Testing to send SMS");
if (gsm.begin(9600)){
Serial.println("\nstatus=READY"); //status that displays if GSM module is active and ready to send sms message
started=true;
} //sets baud rates for arduino and gsm module
else Serial.println("\nstatus=IDLE");

if(started){
if (sms.SendSMS("+1xxxxxxxxxx", "Alert! Child still in seat!"))//sends text message alert to specified phone number
Serial.println("\nSMS sent OK"); //status that displays once sms message was successfully sent
}
};
void loop()
{
};

This code would send sms to my phone. But when I tried to get the GSM module to turn itself on and off using digitalwrite commands, I was no longer receiving messages from the gsm, even though the serial monitor said that the message had sent. I was wondering if trying to make the board turn itself on and off caused this problem and whether or not it could be fixed or if I would need to get a new board. Any feedback would be much appreciated.

Thank You

2

If you put your SIM card from the shield into a phone does it work?

3

Yes.

4

When you upload that code to the Arduino does it still work?

5

When I upload it to the arduino, the code runs normally and the serial monitor says that an sms was sent but nothing happens.

6

Try the 'send' code in the link in my signature and see if you have any more success with that. If not, try the SerialRelay instructions.

7

I already have a code that runs on AT commands and I've been using that to try to see what the problem is.

#include <SoftwareSerial.h>

SoftwareSerial mySerial(50, 51);

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);
SendMessage();
}

void loop()
{
if (mySerial.available())
Serial.write(mySerial.read());
}

void SendMessage()
{
mySerial.println("AT+CMGF=1""\r"); //Sets the GSM Module in Text Mode
delay(500);
mySerial.println("AT+CMGS="+1xxxxxxxxxx""); // Replace x with mobile number
delay(3000);
mySerial.println("Alert!");// The SMS text you want to send
delay(1000);
mySerial.println((char)26);// ASCII code of CTRL+Z
delay(1000);
mySerial.print("AT+CMGDA="DEL SENT"");
mySerial.println();
delay(500);
}

This is the serial response I get

AT+CMGF=1

OK
AT+CMGS="+1xxxxxxxxxx"

Alert!

+CMGS: 108

OK

Based on my observation, it looks like the SIM900 isn't responding to the ctrl+z command and staying in text entry mode until it resets. Would this be a problem with my code or the board itself?

8

Try:

mySerial.write((char)26);
9

It still gives me the same response, sadly.

10

Take a simple SerialRelay program, scan the input from the Serial Monitor checking for a particular character (say carat, '^'). If you receive that character send write(char(26)), otherwise relay the character. Make sure Echo is on so it will repeat your instructions back to the monitor. Then go through the AT commands to send an SMS and see what response you get.

If it replies 'OK' then I'm erring towards a service provider issue.

You have obscured your number - I'm assuming you are in the US?

11

Yes I live in the US

12

Also I thought about what you said regarding service provider issues, so I switched the t-mobile sim card for an at&t sim card and the serial monitor still outputs the same response but this time the message goes through.

13

Which demonstrates that there is no problem with the code or hardware, but there is one with t-mobile?

14

Yes. It appears that both sets of codes work fine. It's just a matter of whether or not the inserted sim card is able to connect to the network. (I found out that my t-mobile account had no money so it wasn't able to send sms even though the sim card could connect with the network.)

15

nick_b:
Yes. It appears that both sets of codes work fine. It's just a matter of whether or not the inserted sim card is able to connect to the network. (I found out that my t-mobile account had no money so it wasn't able to send sms even though the sim card could connect with the network.)

That is why it helps to test the sim card in the phone.

But it is good to hear that you have solved the problem.