Arduino sending sms in GSM sim900 error

0
votes

I have an Arduino Mega 2560 and a sim900 gsm module. I interfaced them successfully and written the code. Its working, but I can only send 1 sms at a time in the while loop. That means when I write a while loop to execute the sendsms() 5 times by using a while loop. Only one sms is sent.. and it stops...

The code is below:

#include <SoftwareSerial.h>
#include <String.h>
SoftwareSerial mySerial(52, 53);

void setup()
{
     mySerial.begin(19200);      // the GPRS baud rate   
     Serial.begin(19200);    // the GPRS baud rate 
     delay(500);

}

int x = 0;

loop()
{

    while (x<5)
    {
     SendTextMessage();  
     x++;
     }  

 }


void SendTextMessage()
{
 mySerial.print("AT+CMGF=1\r");
 delay(100);
 mySerial.println("AT + CMGS = \"+94776511996\"");
 delay(100);
 mySerial.println("hey wow");
 delay(100);
 mySerial.println((char)26);
 delay(100);
 mySerial.println();
}
2
smsarduinogsmat-command

2 Answers

2
votes

You can't just dump your AT commands at the SIM900 with 100mS delay, and expect it to work. The SIM900 responds to AT commands (typically with "OK"), and you should wait for this response before issuing the next command. You can getaway with ignoring these responses only if you provide enough delay between AT commands to make sure that every command is only sent after the SIM900 had enough time to respond to the previous one. To make a quick verification of this, I would add a delay(10000) - a 10 seconds delay - at the end of your sendTextMessage() function. This will (probably) give the SIM900 enough time to complete the SMS transmission before moving on to the next one.

0
votes
void SendTextMessage(){
  mySerial.write("AT+CMGF=1\r\n");
  delay(1000); 
  mySerial.write("AT+CMGS=\"+94776511996\"\r\n");
  delay(1000);
  mySerial.write("Test");
  delay(1000);   
  mySerial.write((char)26);
  delay(2000);
  }