spi.h File Reference

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Macros
SPI duplex mode
Some controllers support half duplex transfer, which results in 3-wire usage. By default, full duplex will prevail.
#define	SPI_FULL_DUPLEX   (0U << 11)
#define	SPI_HALF_DUPLEX   (1U << 11)
SPI Frame Format
2 frame formats are exposed: Motorola and TI. The main difference is the behavior of the CS line. In Motorola it stays active the whole transfer. In TI, it's active only one serial clock period prior to actually make the transfer, it is thus inactive during the transfer, which ends when the clocks ends as well. By default, as it is the most commonly used, the Motorola frame format will prevail.
#define	SPI_FRAME_FORMAT_MOTOROLA   (0U << 15)
#define	SPI_FRAME_FORMAT_TI   (1U << 15)