47.5.3 Sign Extend Serial Data

The SPI allows the user to sign extend data read from the SPIxRXB. This option is only valid for serial words whose length is less than 32-bits. The data in the SPIxRXB is not changed, only on the read of the data does the sign extension occur.

When SPISGNEXT = 1, reads from the SPIxRXB provide 32-bits worth of data. The SPI simply replicates the most significant serial word bit, as defined by AUD- WD_MODE[1,0] or MODE[32,16], though bit 31 of the read data.