SIM900 returns ERROR on SMS commands

[KaareBach]

Hi

I have worked with different SIM900 based boards, but never seen this problem before.
I hope you can help me:

We have developed our own board with a uC and SIM900.
This is tested, and works fine.

But now, suddenly I have the problem, that it returns "ERROR" to almost all AT commands that deals with SMS.

I use these commands:
ATE0 -> OK
AT+CPIN=... -> OK
AT+CSQ -> OK
AT+CMGF=1 -> OK
AT+COPS -> OK
AT+CMGDA -> Returns ERROR
AT+CMGD -> Returns ERROR
AT+CMGR -> Returns ERROR
AT+CSCA -> Returns ERROR
And so on.
Communication is OK, but it just seems like all SMS related commands are gone...
I have tried on to boards, but with same result.


All I have changed is the wall plug supply, and the SIM card.
But using these on the SIM900 Eval board, everything works fine.

I have updated the firmware in my own boards, and at that time, everything worked fine.
No SW changes in the uC since then, so I am really frustrated...

Please, anyone?

br
Kaare

 

[peeyushsigma]

check if CR LF is present in the SMS Command ???

 

[KaareBach]

Every AT command ends with CR+LF.
All other AT commands works fine.

br
Kaare

 

[peeyushsigma]

can u attach the code with schematic diagram...

 

[KaareBach]

Source code and schematic should not be necessary, and I do not have the rights to post it in public.
The board IS working. It HAS been working OK.
Only change is that I am using a different SIM card, and is physically placed 20 km away...

It works with the eval board, but fails on both my own boards.
SIM900 firmwareversion on the eval board is: 1137B09SIM900M64_ST
SIM900 firmwareversion on my boards is: 1137B01SIM900M64_ST_ENHANCE

When I started working on this project, there were a problem with the SIM900 too.
It was fixed by updating the firmware.
I did that on all our prototype boards, and they worked fine.

I am not shure if the firmware is OK, though... It seems like it's an old version, and I don't know what "ENHANCED" is.
I think I have to check out monday.

br
Kaare