I am using the PCS signals on the SPI interface on a Kinetis device (MK20 or MK64).
The signal correctly changes so that's not a problem.
But... how do you determine when the entire transaction has completed i.e. when the PCS signals has returned to its idle state?
The SR.TCF bit only indicates that the last bit has been shifted out. This (obviously) occurs before the PCS signal returns to idle.
I had thought the SR.TXRXS signal might be useful but it doesn't seem to be the case.
Currently I'm polling the PCS signal through the port PDIR register but this is less than elegant - It requires custom code depending on which pin the PCS is mapped to.