I have a MCU board with SPI (3.3V) connector which is driven by SPI master on another board (less than 1 ft cable). What is the best form of protection for the SPI to protect from over voltages for ex connecting it to 5V SPI?
Series current limiting resistors might degrade the signal, right? Will diode clamping the SPI lines to 3.3V rail help? Having parallal schottky diodes for clamping affects signal quality at SPI frequencies? Looking at max SPI clock of 10Mhz.
Thanks in advance
-bj