XR16M890 Overview
The XR16M8901 (M890) is a single-channel Universal Asynchronous Receiver and Transmitter (UART) with integrated level shifters and 128 bytes of transmit and receive FIFOs. For flexibility in a mixed voltage environment, the M890 has 4 VCC pins. There is a VCC pin for the core, a VCC pin for the UART signals, a VCC pin for the CPU interface signals and a VCC pin for the GPIO signals.