USART in Host SPI Mode vs. SPI
The USART in Host 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 Host SPI mode:
- Write Collision Flag Protection
- Double-Speed mode
- Multi-Host support
A comparison of the pins used with USART in Host SPI mode and with SPI is shown in the table below.
| USART | SPI | Comment |
|---|---|---|
| TXD | MOSI | Host out |
| RXD | MISO | Host in |
| XCK | SCK | Functionally identical |
| - | SS | Not supported by USART in Host SPI mode(1) |
Note:
- For the stand-alone SPI peripheral, this pin is used with the Multi-Host function or as a dedicated Client Select pin. The Multi-Host function is not available with the USART in Host SPI mode, and no dedicated Client Select pin is available.