Hi.
I created my own board with the sim900 and use it with my pc over the rs232 interface.
The module works fine but I have a big problem with the gsm location.
I ask for the coords like this:
AT+SAPBR=3,1,"Contype","GPRS"
OK
AT+SAPBR=3,1,"APN","CMNET"
OK
AT+SAPBR=1,1
OK
AT+SAPBR=2,1
OK
AT+CIPGSMLOC=1,1
ERROR
AT+CIPGSMLOC=2,1
I found that in the SIM900_GSM_Location_ATC_V1_00 pdf but it doesn't work.
I found in another thread here, that the command is not implemeted in the original firmware.
So in which one is it implemented or is it impossible to find the coords only over gsm?
Another problem is the audio in and out.
I have a small electret microphone, which i connect straight to the MIC_P and MIC_N pins but nothing happens. Even with the 10 and 33pF capacitors from the datasheet it doesn't work. Its in the Volt range and should work.
The same problem with audio out. I connected a small 8R Speaker straight to the SPK_P and SPK_N pins but there is no output.
I have a LM4861 as an audio power amplifier, but i haven't used it now.
But there should be even a very quite output.
When I call someone, there is only a beep every 2-3 seconds.
Any ideas?
THX