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.
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:
- 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.