So I posted about 10 months ago with a problem regarding my GM862 module and have yet to resolve the problem. I reproduced my original post below with some updated information.
First, using my own serial port code in Linux, I was unable to receive a
response from the device. I opened the serial port, sent the “AT”
command and then the system blocked on a call to read() while
waiting for a response.
Next, via Minicom in Linux, I opened a connection to the device, but
failed to receive a response to the “AT” command (or any other
command).
Finally, I switched over to Windows and duplicated the procedure in
their guide that was on the website and I had the same result. After
sending the “AT” command – or any other command, I failed to receive a response.
I powered down the device between each attempt but was still unable to receive a response.
I tried all of the above both with a SIM card in the modem and without a
SIM card.
Since the post above I have repeated the process above with an external power supply connected to the eval board but I don’t think I’m experiencing a power problem because the status indicator blinks correctly.
I have also used UVCView to check that the cp2102 drivers are functioning correctly.
Lastly I used a port monitoring program to ensure that the correct commands were actually being sent to the device.
At this point I’m thoroughly stuck. I believe that either the module was bad from the get go or the eval board is bad. The only test that I can think of doing is hooking up an oscilloscope to the tx and rx pins on the eval board (at the module connector) to see that the signals are indeed making it to the module. I initially dismissed this as a possibility because I assume that Sparkfun does quality control on their products, I guess we’ll see.
Any other suggestions would be greatly appreciated.
Thanks,
Jason