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GSM module AT commands


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movie_freak



Joined: 20 Mar 2007
Posts: 81
Helped: 2


Post22 Sep 2008 10:03   

at+creg command


Hi,

I am using SIM300d GSM module.

Issue 1:
Are there any AT commands , which can be used to stop +CBM.

I get +CBM: 6128,50,1,1,1
+CBM: 6128,50,1,1,1
+CBM: 6128,50,1,1,1
+CBM: 6128,50,1,1,1
+CBM: 6128,50,1,1,1
+CBM: 6128,50,1,1,1

again and again..and the module hangs for some time during this..

It does it itself i.e. without sending the command AT+CSCB=...

So there must be a way for stopping this..


Issue 2:

My GSM module gets registered automatically with the network as soon as i turn the module on. Now after some duration if i don't have a signal the module gets de-registered. This is all fine.. Now if the signals are available again it does not register by itself with the network.

One possible solution could be whenever the module is de-registered with the network we can cut the power of the module and then restart it again..
But in this case how will i figure it out.. or know when the module is de-registered..


So is there any way of doing it.., if not then how will i figure out the de-registration process..

Many Thanks,

Surya
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srecko



Joined: 11 Oct 2007
Posts: 7
Location: Slovenia


Post22 Sep 2008 10:50   

at command creg


Hello.

I never had such problems with the SIM300D module.
Try using AT+CNMI=0,1,0 to switch off CBM messages.

You can check, if module is registered wit the following command:

AT+CREG?
+CREG: 0,1
OK

If you want to set URC to automatically sends you a message on registration change, use
AT+CREG=1
OK

after this, you will be automatically notified when the module registeres
+CREG: 1,1

and when it deregisteres
+CREG: 1,0

Now you see, that the first parameter is 1. This was set by command AT+CREG=1.

I hope i helped.

BR, Srecko
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movie_freak



Joined: 20 Mar 2007
Posts: 81
Helped: 2


Post23 Sep 2008 11:45   

at+creg gsm


Thanks Srecko,

My exact problem description is as follows:

The module gets registered as soon as it is powered on(with SIM card ). Now if the module is mobile and it gets to a place where the signal strength is really weak, i guess it waits for some timeout and then consider itself as de-registered i.e. AT+CREG? gives CREG: 1,0. And as we saw in our testing this timeout to be some 1or 2 hr or more

The issue is, if the module after this gets a signal with good signal strength it still does not register it back with the network operator, (as in CREG: 1,0) 0 states that it has stopped searching for the network.

To bring back the module into the network we have to cut the power from the module and then again switch it on. Although this is not the ideal way of doing it. Also to do this we need to know when the module is not able to (recieve or send) sms and calls.
One way of knowing this is to wait for CREG: 1,0 which occurs after a long timeout of 1-2hrs which is not desirable. The other way would be to Check for a particular signal strength value after which it stops taking and recieving calls. So, I want to know this particular value of the signal strength.

Also, I would like to know whether there is any other way to avoid this condition or bring back the module into the network without doing all this mentioned above.

Surya
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sabeti_1990



Joined: 16 Nov 2007
Posts: 178
Helped: 11


Post25 Sep 2008 8:57   

gsm at command


hi
it may u have a hardware error or cutting in your antenna by the way check your db signal on module
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Post25 Sep 2008 8:57   

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srecko



Joined: 11 Oct 2007
Posts: 7
Location: Slovenia


Post25 Sep 2008 9:33   

simcom_ltd


Hello.

Is this happening with only one module or with many? It could be also the module's firmware. Did you try with other modules?

BR, Srecko
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movie_freak



Joined: 20 Mar 2007
Posts: 81
Helped: 2


Post25 Sep 2008 10:21   

gsm at+creg


heyy, i'll check about the anntena's but what is the method to measure dB at the module pin..

This has happened in all 3 modules that i tested..

The firmware is:

ATI
SIMCOM_Ltd
SIMCOM_SIM300D
Revision:1008B10SIM300D32_SPANSION

Thanks,

Surya
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movie_freak



Joined: 20 Mar 2007
Posts: 81
Helped: 2


Post27 Sep 2008 6:21   

creg at command


Hi guys,

i have updated the firmware from:

ATI
SIMCOM_Ltd
SIMCOM_SIM300D
Revision:1008B10SIM300D32_SPANSION

to

ATI
SIMCOM_Ltd
SIMCOM_SIM300D
Revision:1008B11SIM300D32_SPANSION


The following table list features or parameters that have been changed or improved compare to
preceding firmware release, version xxxx.

4 Revise a bug that sometimes module can not find network after staying
with a place without network or with very weak signal and returning back
to a place with strong signal.

So guys this was a bug with the firmware.. Now i have updated the firmware and the issue is resolved.. Very Happy
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