25.3.3.1.3.5 USART in Master SPI Mode vs. SPI

The USART in Master SPI mode is fully compatible with a stand-alone SPI peripheral. Their data frame and timing configurations are identical. Some SPI specific special features are, however, not supported with the USART in Master SPI mode:
  • Write Collision Flag Protection
  • Double-Speed mode
  • Multi-Master support

A comparison of the pins used with USART in Master SPI mode and with SPI is shown in the table below.

Table 25-3. Comparison of USART in Master SPI Mode and SPI Pins
USART SPI Comment
TXD MOSI Master out
RXD MISO Master in
XCK SCK Functionally identical
- SS Not supported by USART in Master SPI mode(1)
Note:
  1. For the stand-alone SPI peripheral, this pin is used with the Multi-Master function or as a dedicated Slave Select pin. The Multi-Master function is not available with the USART in Master SPI mode, and no dedicated Slave Select pin is available.