Minimalist-SIM900-Library

Send SMS and web request with a minimalist SIM900 library

Informations

Only a small library who will allow you to send an SMS or a web request in seconds very easily. No need to add a library too full for your project, simply send messages or retrieve data from a web page!

It is a library who shouldn't be on Github, but I don't found a simple library so I hope it right for you!

You can use this code to test your SIM900 shield / module before using my library.

void setup()
{
 Serial1.begin(9600);               // the GPRS baud rate   
 Serial.begin(9600);                 // the GPRS baud rate   
}

void loop()
{
 if (Serial1.available())
   Serial.write(Serial1.read());
 if (Serial.available())
   Serial1.write(Serial.read());  

}

With this program, you just have to open your Serial Monitor at 9600 bauds and send an AT command (you can send a simple command like "AT" without quotes, and see if there is a response from the SIM900).

My library use the MEGA 2560 with RX1 and TX1 (Serial1.begin(9600); ...), so you must have a MEGA 2560, but you also can use the SoftwareSerial library i think i don't run test with this library.

With my SIM900 library and the good SIM900 module, I can send a SMS very quickly in seconds, same for the web request !

Requirements

• An Arduino (MEGA2560 or other but with the SoftwareSerial lib)
• A SIM900 module / shied, I use this SIM900 from SainSmart
• A powerful alimentation who can follow the requirements of the SIM900 module (5V / 2A)
• With the SIM900 from SainSmart i need to connect RX on TX, and TX on RX.

Modifications

You need to specify your APN at SIM900.cpp:35 (because like i say, it just a library for a personnal project, so I don't need to change my APN...)

sendAT("AT+CSTT=\"apn\",\"user\",\"pass\"", "OK", 500);

Examples

You can find this examples in the "examples" folder !

// Send a simple SMS
#include <SIM900.h>

SIM900 gsm;

void setup()
{
  Serial.begin(9600);
  
  gsm.begin("1234"); // 1234 is your PIN
}

void loop()
{
  gsm.sms("0666666666", "Library test"); // 1. your number | 2. the text message
  
  do { } while (1); // send only one SMS
}

// Send a simple web request
#include <SIM900.h>

SIM900 gsm;

void setup()
{
  Serial.begin(9600);
  
  gsm.begin("1234");// 1234 is your pin
  
  gsm.beginGPRS(); // start the gprs and don't forget to change the APN if you need
}

void loop()
{
  String response = gsm.web("ip_or_name", "/adress"); // 1. your ip or hostname | 2. your adress with the "/" before, without the ip, like : gsm.web("127.0.0.1", "/hello.php?id=5&arduino=Mega2560&pin=8");

  delay(900000); // send a web request every 15 minutes
}

Extra

You can use multiple functions to send personnal AT comand with :

sendAT("the at command", "the return string you wait like OK", delay_in_int_to_wait_after_the_command_if_you_need_to_wait_for_a_connection_for_example); // function to send an at command and wait a response from the SIM900 like "OK", if there is no response or an error, there is a timeout of 10 seconds, and you can add an delay to wait after the at command, if you need to wait a connection for example.
// --------------- //
simpleAT("at command"); // minimalist function to simply send an at command
// --------------- //
simpleRead(); // return the Serial1 (SIM900 Serial) buffer

Author

Grégory G. & Laurent T.