USART SPI vs. SPI

The USART in Master SPI mode is fully compatible with the stand-alone SPI module in that:

• Timing diagrams are the same
• UCPHA bit functionality is identical to that of the SPI CPHA bit
• UDORD bit functionality is identical to that of the SPI DORD bit

When the USART is set in Master SPI mode, configuration and use are in some cases different from those of the stand-alone SPI module. In addition, the following difference exists:

• The USART in Master SPI mode does not include the SPI (Write Collision) feature

The USART in Master SPI mode does not include the SPI Double-Speed mode feature, but this can be achieved by configuring the Baud Rate Generator accordingly:

• Interrupt timing is not compatible
• Pin control differs due to the master-only operation of the USART in SPI Master mode

A comparison of the USART in Master SPI mode and the SPI pins is shown in Table 1.