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BenQ M23 connection problem.

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Sep 15, 2007
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I’m trying to connect to a BenQ GSM/GPRS wireless module through hypertherminal but so far i haven’t succeeded.

I’ve just connected the necessary signals (Tx, Rx, SIM card and POWON), power and ground. No more, no less. (yes, I have a level converter for the serial communication between the PC and the module :)
I can communicate for approximately 3 seconds after the power is applied and the POWON is driven low for a few hundred milliseconds. It’s enough for me to write AT and to get the expected response of OK.
Nothing happens when I’m trying to send more characters after the 3 second window is up. Feels like it’s going into a deep sleep mode that I just can’t get it out of.

I’ve noticed that a few people on this forum have experience of the BenQ GSM modules and I was hoping that someone could give me a hint as to what might be my problem. Tried to search the web already but without any luck.



I’ve narrowed the problem down a little bit.
The module works just fine if I remove the antenna so that there can be no communication going on. The communication with the SIM card appears to be working just fine too.
An at+creg? will then of cause return +CREG: 0, 3

Judging by the power usage I would say that it looks like the module is trying to connect to the network but fails in some way. The power usage goes up to about 100mA for a few seconds and then down to about 10mA again. It keeps doing this with an interval of about 10 seconds. It also sends out a few bogus characters between each cycle. I might even get in a
between the cycles.

Yes, the SIM card is working just fine in a normal cell phone.

No takers?? I’m desperate for some help here.


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