SWCU192 November 2021 CC1312R7 , CC1352P7 , CC2652P7 , CC2652R7
Write AUX_SPIM:TX8 or AUX_SPIM:TX16 to transfer 8- or 16-bit data between the SPI master and slaves. Data propagates first to the MSB of the I/O. When transfer completes, MOSI stays at value of the LSB.
An ongoing SPI transfer blocks register access:
The Sensor Controller halts when its access gets blocked, which is then exploited to reduce code size and to save power.