Hi,
when SPI master transmits a data, SPI slave sends a data back to master at the same time. This is a nature of the SPI interface. So, when you want to only transmit a data by master, you will always receive data from slave. You can just disregard such data. When you want to receive a data from slave, master must send some data to slave, so the slave can send the data back. Solution for this is to send a dummy data to slave.
Regards,
Lukas
Hi,
If you want to receive a data from slave, you need to transmit dummy data (like 0xFF), so the slave can clock out the data.
There's an example lpspi_dma:
c:\NXP\S32DS_ARM_v2.2\S32DS\software\S32SDK_S32K1xx_RTM_3.0.0\examples\S32K144\driver_examples\communication\lpspi_dma\
Regards,
Lukas