How to use parity space and mark

[GolamMostafa]

@pimaliao

Communication between the client and server occurs through a serial data link operating at 19.2 K in a "wakeup" mode,eight data bits, a ninth ‘wakeup’ bit, and one stop bit.
According to this protocol, the server needs to read the 9th bit (the parity one) and to decide by itself if that's the start byte of a new message (parity bit is "1") or (parity bit is "0").

Is it an asynchronous serial data communication? If so, the TXD line is always at HIGH state and it gets pull-down for 1-bit period to indicate the START of a new frame and then comes the 8-data bit with LSB first and then the Parity Bit (Even or Odd) and then the STOP Bit. The following diagram of Fig-1 shows an asyn frame of 11-bit length with even parity option. This frame will be automatically generated with Bd = 9600 when the following code is included in a sketch.

Serial.begin(9600, SERIAL_8E1);//1 START Bit, 8 Data Bits, 1 Even Parity Bit, 1 STOP Bit.

Figure-1: