Communicating with Phone
1) Communicating with the phone
As said earlier, communication with the phone is full duplex 8 bits, no parity, 1 stop bit and @115200 bauds.
So when connecting the AT89S52 microcontroller to the phone you have to setup baud rate of 115kbps using Timer 2. To initiate the communication we have to send character ‘U’ or 0x55 128 times to the phone. That’s all. The race track is ready now!