Hi all, I am using MCB900 devolepment kit with P89LPC935 micro. I want to communicate with my Samsung D500 to send data. The micro can recieve data from the GSM but when sending the data from micro to the GSM no response is coming from the phone. I connect the micro to my pc and sending it the exact command reciving from the phone and the micro sends me the initialization bytes to the PC but the same code is sent to the GSM but phone doesnot initialize. Connecting the GSM to hyper terminal works fine, but connecting it to the microcontroller not initializes, any help is appreciated. I use the ports as quasi-bidirectional by setting P1M1=0x00 and P1M2=0x00; but still the micro can recive data and sends it correctly but GSM does not respond on it.
The PC has a RS232 transciever. Evidently your circuit does not. Maybe you believe in the urban legend that uC pins can drive RS232 directly. Erik