Issue with SPI slave driver in S32K148 - MBF flag always set

[sgp_118]

Hi All,

I am trying to develop a SPI slave driver for S32K148. In that, as soon as I do slave Init, I see the MBF bit in Status register is always set. I couldn't see any detailed explanation of what this bit means. 

Is there any detailed application note available for SPI master/slave communication?

Also I am looking for reference to develop a SPI slave which doesnt need CS pin.

Any help on this will be highly appreciated.

Regards,

Guru

[danielmartynek]

Hi Guru,

It could be if it S32K148 LPSPI Slave receives SCK and the TX FIFO underflows and the RX FIFO overflows.

Regards,

Daniel

[sgp_118]

Thanks for the reply, Daniel.

Right now we have a trouble in HW at master side, due to which PCS pin always remain low (ie., it nevers goes to Idle High state). And I observe TEF and REF error flags are set in Status register. Can those error conditions be attributed to the fact that PCS remains LOW always?

Regards,

Guru

[danielmartynek]

Hi Guru,

I was able to reproduce this condition when I set the PCS polarity LOW and pulled the PCS pin LOW.

Once the LPSPI module gets enabled, it expects a frame and reports a BUSY state.

Please take a look at the answer here:

https://community.nxp.com/t5/S32K/Communicating-with-SPI-slave-driver-without-using-ChipSelect-pin/t...

Thank you,

BR, Daniel