Serial Port

The MCB900 board connects the on-chip serial UART to the MAX3221 (IC1), which converts the logic signals to RS-232 voltage levels. The UART is used to communicate with the PC for programming and debugging.

The MCB900 board connects directly from COM1 to a PC using a standard DB9 serial cable.

The serial UART port (COM1) is configured as a standard 3-wire interface. The DB9 connector is wired to loop the PC's handshaking signals back to the PC. Refer to the figure below for details.