uart.md

The UART

8-N-1 UART

• Default base address is 0400h
• Baud rate is set using the BAUD_DIV parameter of the toy module
• Can launch interrupt when data is available for reading or when a receive error is detected.

Registers

• Data register (at 0400h)

  • Writes trigger serial transmit
  • Reads clear the status register
  • High byte is ignored (or zero when reading)

• Status register (at 0401h)

  • Contains Tx and Rx status flags
    • bit 0: Tx ready (idle)
    • bit 1: Rx error
    • bit 2: Rx data available
  • data cannot be written into status register, write access clears the Rx status flags.