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[SOLVED] +CPIN: NOT READY on SIM900

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ulrikp

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Hi,

I'm using a SIM900 module, and usually it works fine, but lately it has started giving the error "+CPIN: NOT READY". As soon as I get this message, the voltage on SIM_VDD drops to 0V. The problem is intermittent (i.e. it happens only sometimes).

It seems to happen more often on 3V SIM cards than on 1.8V sim cards. If it happens on a 3V SIM card, I can switch to 1.8V SIM card, and the problem is temporarily solved, and vice versa.

I have read all related posts on here. Here is some info on my setup:
-Schematics is designed according to SIM900 documentation.
-I use 6-pin SIM connector.
-Firmware is B10. I have tried with B11, and it makes no difference.
-Changing input power does not help. I have tried with up to 12V, 2A.
-Adding decoupling caps on SIM_VDD, on input power, and on VBAT (for SIM900) does not help.
-Signal strength is fine (about CSQ=20).

The "+CPIN: NOT READY" is sent at different times, however, often quite soon after power on. Below is a typical situation.

%%%%%%%%%%%%%%%
IIII
RDY

+CFUN: 1

+CPIN: READY

Call Ready

+CPIN: NOT READY
%%%%%%%%%%%%%%%

If it doesn't happen as above, I can often make the problem occur by trying to make a voice call ("atd nnnnnnnn;")


Can someone please help out?

Thanks!
Ulrik
 

The problem was solved with the help of GSM Man: If you communicate with SIM900 before the module has sent the unsolicited message: "Call Ready", then you might get this problem. I now wait to communicate until after receiving "Call Ready" from the module, and all problems are solved.
 
Hi, did your problem solved?

We have exactly the same situation like yours, but we communicate until after receiving "Call Ready" from the module, The problem still remain.

Can you give us some suggestions? I really appreciate that.

Thanks

Emma





ulrikp said:
Hi,

I'm using a SIM900 module, and usually it works fine, but lately it has started giving the error "+CPIN: NOT READY". As soon as I get this message, the voltage on SIM_VDD drops to 0V. The problem is intermittent (i.e. it happens only sometimes).

It seems to happen more often on 3V SIM cards than on 1.8V sim cards. If it happens on a 3V SIM card, I can switch to 1.8V SIM card, and the problem is temporarily solved, and vice versa.

I have read all related posts on here. Here is some info on my setup:
-Schematics is designed according to SIM900 documentation.
-I use 6-pin SIM connector.
-Firmware is B10. I have tried with B11, and it makes no difference.
-Changing input power does not help. I have tried with up to 12V, 2A.
-Adding decoupling caps on SIM_VDD, on input power, and on VBAT (for SIM900) does not help.
-Signal strength is fine (about CSQ=20).

The "+CPIN: NOT READY" is sent at different times, however, often quite soon after power on. Below is a typical situation.

%%%%%%%%%%%%%%%
IIII
RDY

+CFUN: 1

+CPIN: READY

Call Ready

+CPIN: NOT READY
%%%%%%%%%%%%%%%

If it doesn't happen as above, I can often make the problem occur by trying to make a voice call ("atd nnnnnnnn;")


Can someone please help out?

Thanks!
Ulrik
Click to expand...
 

Hi,

I think this problem can have many different causes. In my case, I think the root of the problem is noise from the antenna onto the SIM card. It seems to happen more frequently if I communicate before receiving "Call Ready".

Please upload your schematics (or send PM to me). If possible, also post a photo of the hardware.
 

Hi,
I am using a SIM900A module, it works fine with vodafone and T24 SIM. However, when I use Airtel or BSNL or Idea, I get the error "+CPIN: NOT READY" and network registration does not happen. Any pointer for solution of this problem is highly appreciated.
Regards,
Kishore
 

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