SIM900 ICOMSAT 1.1 does not send sms

The SIM900 is coupled to the arduino uno r3, I’m not using any wires.
The code:

#include <SoftwareSerial.h>
SoftwareSerial mySerial(2,3);
char flag=0;
void setup()
{
delay(30000);
mySerial.begin(19200);
Serial.begin(19200);
}
void loop()
{
if(flag==0)
{
mySerial.print(“AT+CMGF=1\r”);
delay(1000);
mySerial.print(“AT+CMGS=”+5519993210000"\r");
delay(1000);
flag=1;
}

if(flag==1)
{
mySerial.print(“Hello SIM900 and Arduino!\r”);
delay(1000);
mySerial.write(0x1A);
delay(1000);
flag=2;
}
if(flag==2)
{
Serial.println(“OK!”);
delay(5000);
flag=3;
}
}

Appears OK message! but nothing is sent.

i have the same problem :3

Check this code,it can help you, I sent some SMS by it.

#include <SoftwareSerial.h>
SoftwareSerial SIM900(7, 8);
 
void setup()
{
  SIM900.begin(19200);
  SIM900power();  
  delay(20000);  // give time to log on to network. 
}
 
void SIM900power()
// software equivalent of pressing the GSM shield "power" button
{
  digitalWrite(9, HIGH);
  delay(1000);
  digitalWrite(9, LOW);
  delay(5000);
}
 
void sendSMS()
{
  SIM900.print("AT+CMGF=1\r");                         // AT command to send SMS message
  delay(100);
  SIM900.println("AT + CMGS = \"+21267315xxxx\"");     // recipient's mobile number, in international format
  delay(100);
  SIM900.println("Hello ^^");        // message to send
  delay(100);
  SIM900.println((char)26);                       // End AT command with a ^Z, ASCII code 26
  delay(100); 
  SIM900.println();
  delay(5000);                                     // give module time to send SMS
  SIM900power();                                   // turn off module
}
 
void loop()
{
  sendSMS();
  do {} while (1);
}

I have problem, I used the example in library send sms, and in the serial monitor just appear Send sms messages, I waiting, and there is nothing happen,, I am new in arduino user, please help.... thanks before

I use the icomsat 1.1 as the shield,, I hve just bought it two days ago,, what is the shield you use? also,, I hve tried the other gsm example in library, like receive, make call, check modem, gsprs,, and problem is same Help please...

The examples provided with the IDE are for the official Arduino GSM/GPRS shield, which uses the Quectel M10 chip, not the SIM900.

This section of the forum is for dealing with issues with the official shield.

Now we have got that out of the way, how have you got the I/O jumpers set on your IComsat?

The I/O, I just plug on the arduino uno
I have tried using the other tutorial which for sim900, but itssame
I am new i arduino user, so I learning about that,

Set the jumpers are per the (hopefully) attached photo. I’ve used yellow so they stand out.

Then use

SoftwareSerial SIM900(6, 7);

in the code krikho1994 posted above.

so I change the SoftwareSerial SIM900(7, 8); in krikho1994 code with SoftwareSerial SIM900(6, 7);

its works!!! thank you so much you all especially for dannable,

to dannable: why its must be pin 6 7??

They are the ones you selected with the jumpers. You can select any pair from D0 to D7, just change the software to reflect this. Unless you have good reason to, never use D0 & D1 because the hardware serial uses these pins, meaning Serial Monitor won't work.

On that shield D8 is reset and D9 is power.

ok, many thanks to you dannable,,

Hai I'm also using icomsat 1.1 with arduino uno and follow this thread. After i read this article then i try, but it still cannot send sms by this code? why is it happen? can you help me dannable? i'm using krikho1994s code anyway.

So you have set the jumpers as per the photo, and changed the code to reflect this?

If so, have you tried a simple serial relay program just to test communications?

yeah, i have.
how to do that? i never know about it. when i press the power button on shield status green but NET wink every 3 second

now i’m using software arduino 1.6.4. when i compiled it, it attach to the arduino. when open serial monitor nothing happen although there is nothing error.

#include <SoftwareSerial.h>
SoftwareSerial SIM900(6, 7);
 
void setup()
{
  SIM900.begin(19200);
  SIM900power();  
  delay(20000);  // give time to log on to network. 
}
 
void SIM900power()
// software equivalent of pressing the GSM shield "power" button
{
  digitalWrite(9, HIGH);
  delay(1000);
  digitalWrite(9, LOW);
  delay(5000);
}
 
void sendSMS()
{
  SIM900.print("AT+CMGF=1\r");                         // AT command to send SMS message
  delay(100);
  SIM900.println("AT + CMGS = \"+6289638777223\"");     // recipient's mobile number, in international format
  delay(100);
  SIM900.println("Hello ^^");        // message to send
  delay(100);
  SIM900.println((char)26);                       // End AT command with a ^Z, ASCII code 26
  delay(100); 
  SIM900.println();
  delay(5000);                                     // give module time to send SMS
  SIM900power();                                   // turn off module
}
 
void loop()
{
  sendSMS();
  do {} while (1);
}
  delay(100);

Try increasing all of these to one second:

  delay(1000);

well i do have same issue right here. i work on this code, which exactly the same with the example given by krikho. I only change the software serial pins into 2,3 (i already matched it with I/O pins on my SIM900) dannable said that it is okay since not using 1 and 0

#include <SoftwareSerial.h>
SoftwareSerial SIM900(2, 3);

 
void setup()
{
  SIM900.begin(19200);
  SIM900power();
  delay(20000);  // give time to log on to network. 
}
 
void SIM900power()
// software equivalent of pressing the GSM shield "power" button
{
  digitalWrite(9, HIGH);
  delay(1000);
  digitalWrite(9, LOW);
  delay(5000);
}
 
void sendSMS()
{
  SIM900.print("AT+CMGF=1\r");                                                        // AT command to send SMS message
  delay(1000);
  SIM900.println("AT + CMGS = \"+628569xxxxx\"");                                     // recipient's mobile number, in international format
  delay(1000);
  SIM900.println("Hello, world. This is a text message from an Arduino Uno.");        // message to send
  delay(1000);
  SIM900.println((char)26);                       // End AT command with a ^Z, ASCII code 26
  delay(1000); 
  SIM900.println();
  delay(5000);                                     // give module time to send SMS
}
 
void loop()
{
  sendSMS();
  do {} while (1);
}

done with the compiling, i uploaded the code to board. and nothing happened.

  1. This code supposed to automatically turned ON the shield, isn’t it? Since there is SIM900power() inside the code. But my shield still turned OFF. I still have to press the power button to turn it ON. I also used external adapter just in case the current was’nt enough from the USB. But nothing changed.

  2. The shield doesn’t send the message.

I really need help

The following works for me. Txd jumper on 2, Rxd on 3, slide switch to ‘UART’. Note the additional declaration of the powerPin as OUTPUT.

#include <SoftwareSerial.h>

#define powerPin 9

SoftwareSerial SIM900(2, 3);


void setup()
{
  pinMode(powerPin,OUTPUT);
  digitalWrite(powerPin,LOW);

  SIM900.begin(19200);
  SIM900power();
  delay(20000);  // give time to log on to network. 
}

void SIM900power()
// software equivalent of pressing the GSM shield "power" button
{
  digitalWrite(powerPin, HIGH);
  delay(1000);
  digitalWrite(powerPin, LOW);
  delay(5000);
}

void sendSMS()
{
  SIM900.print("AT+CMGF=1\r");                                                        // AT command to send SMS message
  delay(1000);
  SIM900.println("AT + CMGS = \"+447751123456\"");                                     // recipient's mobile number, in international format
  delay(1000);
  SIM900.println("Hello, world. This is a text message from an Arduino Uno.");        // message to send
  delay(1000);
  SIM900.println((char)26);                       // End AT command with a ^Z, ASCII code 26
  delay(1000); 
  SIM900.println();
  delay(5000);                                     // give module time to send SMS
}

void loop()
{
  sendSMS();
  do {
  } 
  while (1);
}