USART?:
  _modify:
    UCSR?A:
      access: read-write
  UCSR?A:
    _modify:
      UPE?:
        access: read-only
      DOR?:
        access: read-only
      FE?:
        access: read-only
      UDRE?:
        access: read-only
      TXC?:
        description: "USART Transmit Complete"
      RXC?:
        access: read-only
  UCSR?B:
    _modify:
      RXB8?:
        access: read-only
  UCSR?C:
    UMSEL?:
      _replace_enum:
        USART_ASYNC: [0, "Asynchronous USART"]
        USART_SYNC:  [1, "Synchronous USART"]
        SPI_MASTER:  [3, "Master SPI (MSPIM)"]
    UPM?:
      _replace_enum:
        DISABLED:    [0, "Disabled"]
        PARITY_EVEN: [2, "Enabled, Even Parity"]
        PARITY_ODD:  [3, "Enabled, Odd Parity"]
    USBS?:
      _replace_enum:
        STOP1: [0, "1-bit"]
        STOP2: [1, "2-bit"]
    UCSZ?:
      CHR5: [0, "Character Size: 5 bit"]
      CHR6: [1, "Character Size: 6 bit"]
      CHR7: [2, "Character Size: 7 bit"]
      CHR8: [3, "Character Size: 8 bit"]
    UCPOL?:
      _replace_enum:
        RISING_EDGE:  [0, "Transmit on Rising XCKn Edge, Receive on Falling XCKn Edge"]
        FALLING_EDGE: [1, "Transmit on Falling XCKn Edge, Receive on Rising XCKn Edge"]