25.5.1 Control A

Name: CTRLA
Offset: 0x00
Reset: 0x00
Property: -

Bit 76543210 
  CSIG[1:0]  CMODE[1:0]ENABLE 
Access R/WR/WR/WR/WR/W 
Reset 00000 

Bits 6:5 – CSIG[1:0] Communication Signals

These bits select the pins used in communication. All input pins except for CTS are optional for all settings.
ValueNameDescription
0x00 NORMAL

Normal Asynchronous USART (TXD, RXD), Synchronous USART (TXD, RXD, XCK) or SPI host (MOSI, MISO, SCK)
0x01 RS485

Asynchronous USART in RS485 mode (TXD, RXD, XDIR).
0x02 HANDSHAKE

Asynchronous USART with Hardware Handshake (TXD, RXD, RTS, CTS).
0x03 CLKDIS

SPI Host or Synchronous USART host without clock output (MOSI, MISO or TXD, RXD)

Bits 2:1 – CMODE[1:0] Communication Mode

These bits select the communication mode of the USART.
ValueNameDescription
0x00 ASYNCHRONOUS Asynchronous mode
0x01 SYNCCLIENT Synchronous client mode
0x02 SYNCHOST Synchronous host mode
0x03 SPIHOST SPI Host

Bit 0 – ENABLE Enable

Writing this bit to ‘1’ enables the USART.
ValueDescription
0 The USART is disabled
1 The USART is enabled