Arduino UNO & SIM900 -AT communicaton problem

Projects Networking, Protocols, and Devices
28

The Ý Ý Ý Ý Ý Ý is due to a communication error related to auto-bauding. Nothing other than typing "AT" or "At" will result in synching up with the Shield. I am glad yours works. For those having the issue described above need only follow as defined.

Andr3s:
Hello jgalaxy I could communicate with arduino sim900. The problem was that these Ý Ý Ý Ý Ý Ý coming out in the beginning is that this in Chinese, but that means it's working. I used the sscom32 to send commands and functions, write an "at" and you respond OK. and it then call and send mensajs achieved. Any questions you have write me;) an mp or email andres.olivares @ outlook.com. Greetings.

jgalaxy:
I havent heard from the original poster.
I'm still trying with no luck.
I have tried uninstalling and removing the UNO drivers and re-installing.
I have tried different baud rates from 300 to 115200 in the serial monitor.
I have tried going to Device Manager and setting the baud, parity and flow control there and then going through all the baud rates using serial monitor.
No luck.

Andr3s:

Gallentro:
Hi there

I do actually have a very similar problem, that I haven't found the solution yet.
I'm trying to control a SIM900 mounted on a Efcom Pro (http://www.elecfreaks.com/wiki/index.php?title=EFCom_Pro_GPRS/GSM_Module) with my UNO. I sticked to the tutorial on said wiki and ended up with the following code (arduino 1.0.3):

#include <SoftwareSerial.h>

SoftwareSerial mySerial(2, 3);

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

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

}




Than hooked up the serial connection from the Efcom Pro to pins 2 and 3 and started my serial monitor and turned on the Efcom Pro. As expected the chip sent out some data upon turning on, but it looked like this: Ý Ý Ý Ý Ý Ý .

Trying to communicate with it through AT commands did nothing at all, no reply. I see from the blinking on the Efcom Pro, that it has registered with the network, but it's not reachable through the serial connection.

Any suggestions?

hello, I have the same problem. You found the solution to this problem? sorry for my English I speak Spanish.