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 1. 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.