Sim 800c sending corrupted messages

Projects Programming
1

Hi there,

I am using Arduino Uno with sim800c. The tx and rx are connected to arduino with 1k resistors as described in the datasheet.

#include <SoftwareSerial.h>

SoftwareSerial mySerial(11, 10);

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);
}


void loop()
{
  if (Serial.available()>0)
   switch(Serial.read())
  {
    case 's':
      SendMessage();
      break;
    case 'r':
      RecieveMessage();
      break;
  }

 if (mySerial.available()>0){
  Serial.write(mySerial.read());
 }

}


 void SendMessage()
{
  mySerial.println("AT"); 
  delay(1000);
 
}


 void RecieveMessage()
{
  mySerial.println("AT+CNMI=2,2,0,0,0"); // AT Command to receive a live SMS
  delay(1000);
 }

This is the code I am using. When I send the command "AT" it sends AK instead of OK. This is the problem with all the AT commands.

2

the forum is inactive >:( its been 3 days no reply

3

There's not much to go on. It would help to see your schematic - specifically how you have it wired up, not what the data sheet calls for although a link to that wouldn't go amiss.

Normally I would suggest trying something simpler, but it's hard to get much more simple that what you have. Perhaps try sending anything you read from serial direct to the Sim, echoing it's response back.

Then you can try some AT commands that return more than just OK to see if you're getting more corruption or indeed consistant corruption.