SWRU543B January 2019 – June 2025 CC3230S , CC3230SF , CC3235MODS , CC3235MODSF , CC3235S , CC3235SF
The slave transmit and receive mode is programmable (TRM bits set to 00 in the register SPI_CHCONF). After the channel is enabled, transmission and reception proceed with interrupt and DMA request events.
In slave transmit and receive mode, the transmitter register should be loaded before the SPI is selected by an external SPI master device. The transmitter register or FIFO (if the use of a buffer is enabled) content is always loaded in the shift register, whether updated or not. The TX_underflow event activates, and does not prevent transmission.
Upon completion of SPI word transfer (the EOT bit of the SPI_CHSTAT register is set), the received data is transferred to the channel receive register. This bit is meaningless when using the buffer for this channel.
The built-in FIFO is available in this mode and can be configured in one data direction, either transmit or receive, to ensure that the FIFO is seen as a unique 64-byte buffer. The FIFO can also be configured in both data transmit and receive directions, to ensure the FIFO is split into two separate 32-byte buffers with individual address space management. In this last case, the definition of the AEL and AFL levels is based on 64 bytes, and is the responsibility of the local host.