Using IMXRT1060 we send 16 bits SPI as master and everything works fine. We have a 20 ohm resistor on the SCK signal.
When we remove the resistor, the NXP does not stop after 16 clocks, but rather keep on until the FIFO's are full.
We are using the exact same code for both scenarios.
I am wondering how does a resistor on SCK (which is a master output pin) cause the master to keep on clocking past the transaction boundaries?
We never touch the CONT/CONTC bits and not using DMA or interrupts.
Following is an image of a good and bad flow:
