Some problems about GPRS

Q: I just received an GPRS shield v1.4 from Seedstudio. I’m trying to do like
in WIKI and it’s not working. If I send something through SSCOM32E from wiki
page, I received 00 00 00 00 (hex) and not “OK”. What’s wrong with that in
GPRS shield ?

That is the problem. I don’t see nothing in SSCOM32E. If I send “AT”, the module should response with “OK” and not “00 00”.
You write it in your WIKI, about setting “AT+IPR=19200” and “AT”, and the response SHOULD be “OK”, but it is NOT. My response is “00 00” (hex).
I cannot see “OK” in the screen.

A:There are something errors with your baud rate setting.You need find your baud rate and reset it again.

1)Edit your demo on Arduino ADK:
void setup()
{
GPRS.begin(1200); // the GPRS baud rate
Serial.begin(19200); // the Serial port of Arduino baud rate.
}
and then,upload it.
Open your SSCOM3.2 port,set it to operate at 19200 8-N-1 and then click “Open Com”. you should click the “send new” option,and then send AT command “AT”.
whether The modem respond with an OK? If yes,send AT command “AT+IPR=19200”,and close your SSCOM3.2,then edit demo “GPRS.begin(19200);”,upload it.All finished.

If no,continue testing.
2)Edit your demo on Arduino ADK:
void setup()
{
GPRS.begin(2400); // the GPRS baud rate
Serial.begin(19200); // the Serial port of Arduino baud rate.
}
and then,upload it.
Open your SSCOM3.2 port,set it to operate at 19200 8-N-1 and then click “Open Com”. you should click the “send new” option,and then send AT command “AT”.
whether The modem respond with an OK? If yes,send AT command “AT+IPR=19200”,and close your SSCOM3.2,then edit demo “GPRS.begin(19200);”,upload it.All finished.

If no,continue testing.
3) Steps like previous:
GPRS.begin(4800/19200/38400/57600/115200);

Note: when you have finally changed the baud rate of GPRS,please modify the baud rate of Serial port too: GPRS.begin(2400);Serial.begin(2400)//or others.

If you find the right baud rate,you can start to use GPRS shield.Good luck.

Also, you can use UartSBee to change Baud rate ,and it’s more simple.

Hi, I am having similar problems. I tried the process you described, but it still didn’t work. Chaning the baud rate to 2400 in the Arduino code gives readble serial output, but when I try the AT+IPR=19200 command, it does not work. Sending “AT” works ok. I cannot delete SMS messages in memory either. It seems the problem is that I cannot enter a command of more than about 5 characters long. It is really wierd. Can you please help? It is really frustrating and I cannot use my GPRS and I really need to.

Hi,could you please post your picture of errors?

And whethter you use SSCOM32E to test?

Hi,
Yes I can provide some screenshots of the problems soon. I get the same results using both SSCOM32E or the Arduino Serial monitor.

hi all,there are some friends first come to our shield,and don’t know how to use it with Arduino Mega.Following picture is the connection.

Hi Jacket,
Sorry for the delay. Please see the attached screenshot. I used the solution as suggested above - in the demo code I used a baud of 2400. Then, my first command was “AT”, which I received an "OK. Then my second command was AT+IPR=19200 as you can see in the screenshot. However, as a response I received “AT+920”. The solution doesn’t work for me and I get strange behaviour which I change the demo code back to 19200. It seems that the shield cannot receive an AT command of more than 2-3 characters - it get’s jumbled. (?). Can you please help - this is really frustrating and I cannot use my shield.
Cheers
Dan
ssComScreenshot.jpg

Hi again,
It’s been some time. I have since tried with multiple Arduino’s and they all give the same results - after I type “AT+IPR=19200” I get a return of “AT+920”. It must be something wrong with my Seeedstudio GPRS shield. It must be broken…? What can I do? Can you please help?

Hey , whether you have modified the program ? And maybe you have your own program? Could you show me the demo?

Hello,

I´me having exactly the same problem. Did any one found a solution?

Regards,
Hugo Gomes

I solve this problem by resetting the SIM900 chip (pin16 of SIM900 to ground). After this I could change the baud rate with the “AT+IPR=…” command normally.

I still don´t know what cause the malfunction in the first place.

Regards,
Hugo Gomes