GSM not responding to pic
Posted:
Sat Mar 03, 2012 1:20 pmby wan88
I'm working on the GSM+pic project on both
http://tutorial.cytron.com.my/2011/12/08/control-and-monitor-via-sms/ and
http://shahrulnizam.com/pic-lesson-gsm-modem/. Unfortunately I didnt receive any response from the GSM. Im using iTegno 3832 modem. I've check the GSM with HT and its working fine. Can anyone help me with a solution
Re: GSM not responding to pic
Posted:
Sat Mar 03, 2012 10:23 pmby shahrul
Post your schematic and hardware photo.
Re: GSM not responding to pic
Posted:
Sun Mar 04, 2012 10:09 amby wan88
Re: GSM not responding to pic
Posted:
Tue Mar 06, 2012 11:01 amby wan88
I've measure the voltage across pin 13 for max232 and i get -7V. I also notice that there is no voltage across pin 14 max232. Are this suppose to happened?
Re: GSM not responding to pic
Posted:
Tue Mar 06, 2012 11:24 amby shahrul
wan88 WROTE:I've measure the voltage across pin 13 for max232 and i get -7V. I also notice that there is no voltage across pin 14 max232. Are this suppose to happened?
Pin 14 is transmit, should have voltage. Look your picture, I'm not sure what capacitor value you use. It should be electrolitic capacitor (not ceramic) with value 10uF.
Re: GSM not responding to pic
Posted:
Tue Mar 06, 2012 11:36 amby wan88
TQ for the reply. I've been figuring this out for ages now. I will try and change the capacitor
Re: GSM not responding to pic
Posted:
Tue Mar 06, 2012 12:29 pmby wan88
I've change the capacitor and still it give the same voltage and no GSM response.
Re: GSM not responding to pic
Posted:
Tue Mar 06, 2012 12:39 pmby shahrul
wan88 WROTE:I've change the capacitor and still it give the same voltage and no GSM response.
The best thing, you see the waveform with oscilloscope. Check pin 11, 14, 13, 12 of MAX232. This is step beginner should do.
Re: GSM not responding to pic
Posted:
Mon Mar 12, 2012 8:19 pmby robosang
Er... why don you test your MAX232 circuit with a computer COM Port. Since the microcontroller should send some text to Modem. So now use the computer as modem, bare in mind you will need to cross the Tx and Rx line if you are sending it to computer, and later when you are done with computer, swap back the Tx and Rx.
Re: GSM not responding to pic
Posted:
Mon Mar 12, 2012 9:28 pmby wan88
robosang WROTE:Er... why don you test your MAX232 circuit with a computer COM Port. Since the microcontroller should send some text to Modem. So now use the computer as modem, bare in mind you will need to cross the Tx and Rx line if you are sending it to computer, and later when you are done with computer, swap back the Tx and Rx.
can u guide me how to do that? or maybe a link to help me?
