GSM/GPRS shield, open GPRS connection

Using Arduino Networking, Protocols, and Devices
1

Hi !

I've buy a GSM/GPRS shield for arduino (see on aliexpress) with the aim to learn how it's work for fun :wink:

The shield is working : I've already successfully sent and received SMS.

But now I'm trying to get the content of a webpage through GPRS, and it isn't the same story.

This is the program in the board (Arduino UNO), this is just a short program to send AT command with the serial monitor & print the return of the shield :

#include <SoftwareSerial.h>

SoftwareSerial gsm(2, 3);

void setup() {
  Serial.begin(9600);
  gsm.begin(9600);
  Serial.println("Ready");
}

void loop() {
  if (gsm.available()) {
    Serial.write(gsm.read());
  }
  if (Serial.available()) {
    char c = Serial.read();
    gsm.write(c);
  }
  delay(10);
}

So this is the suits of command I sent :

AT+SAPBR=3,1,"Contype","GPRS" // RETURN OK
AT+CSTT="sl2sfr","","" // RETURN OK, but maybe the error is here
AT+SAPBR=1,1 // RETURN ERROR, so sad :(

// Naturally the rest doesn't work
AT+HTTPINIT
AT+HTTPARA="CID",1
AT+HTTPARA="URL","http://atomicserver.io:8080"
AT+HTTPACTION=0
AT+HTTPREAD"

I'm not an expert of network, so I have no idea where the problem comes from, indeed the "ERROR" returns is not a great help. Moreover the return of AT+CEER is as follows: "+CEER: No Cause".

Reflection track :

  • The shield is not compatible with the French network.
  • The APN ID is not good. I tested with another identifier and the shield returns "ERROR", I deduce that it is good. That said, I couldn't find an APN specific to the GPRS network for my operator, the problem may come from here ...

Note : I tried the SIM on a phone, I have a 3G/4G access (difficult to test GPRS on an iPhone...)
I'm in France, my operator is SFR (I don't know if that can help).

Thank you in advance for your help, and please excuse my approximate English :wink:

EDIT : The return of AT+SAPBR=1,1 is now "+CME ERROR: operation not allowed" (with AT+CMEE=2)

2

Hi,

I finally resolve the problem myself.

I don't know why the AT+CSTT="sl2sfr","","" doesn't work but I solved it by doing AT+SAPBR=3,1,"APN","sl2sfr" instead. Maybe it's because the APN has no password.

I also made a second mistake, there is a typo on the HTTPARA command which is in fact HTTPPARA (with two 'P').

Hope this can help :wink:

PS : If someone know why the AT+CSTT="sl2sfr","","" fails, I am always interested.

Thanks.