GSM not responding to pic

[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

[shahrul]

Post your schematic and hardware photo.

[wan88]

I'm using the schematic and coding provided by the projects. This is the pic of my hardware for your blog project

[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?

[shahrul]

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.

[wan88]

TQ for the reply. I've been figuring this out for ages now. I will try and change the capacitor

[wan88]

I've change the capacitor and still it give the same voltage and no GSM response.

[shahrul]

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.

[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.

[wan88]

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?