Hi,
I am working with SIM900A GSM module. I was testing it by sending ""AT\r\n" but it is responding by string ERROR. I am using PIC18F452. The same code was working well with SIM300 but SIM900A is responding with ERROR. And when used with PC it is working correctly it is giving correct OK response on PC but not with MCU. I have tried extracting large data also from SIM300 with success but SIM900A seems some what different, but AT commands are same at least basic. Any help would be appreciated.