13.2.2.6.1 SPI Slave Frame Format

The frame format consists of a command frame followed by 0 to 31 data frames. The size of the command frame and data frame must be equal and is defined by TXRXDFS. A typical use model would be to define the command frame as 8 bits followed by 31 bytes of data. This assumes BIGFIFO is set to 1 and TXRXDFS is set to 0x08.

The following figure shows the command and data bytes. Transmit and receive refer to the SPI peripheral as the slave. Data bytes are optional.

Figure 13-15. SPE Command/Data Format

The first receive byte of the sequence after SPI_X_SS[x] asserts is always a command byte. The slave always responds with a status byte, which is the contents of the Table 13-24 register.

Important: Set two bits in the HWSTATUS register to facilitate additional handshaking schemes between SPI master and SPI slave.