We are using imx6UL chip MCIMX6G0DVM05AA in our board where in we have configured below pins:
These pin are being used to communicate with a MCU (STM32F7) on other board . The connectivity is done over a wire harness with length of around mm. We have put series termination resistor on i.e. the SCLK, MISO and MOSI signal tuned to keep the over shoot in signal level with in acceptable range of voltage i.e. Vdd(3.3V) +0.6V.
But we are observing that these pins are getting damaged very frequently. Even NSS pin which is not switching at very high frequency got damaged some time.
Do we need to put some other protection device on these pins. Our SPI communication is working on 12MHz.
Please find below interface diagram for SPI Bus