Weird SPI interface: VIH to VIHH for CS?

[mister_e]

What you need to worry is your PIC I/O, some could be Open-Collector type, so if you use a open collector I/O as output, you need to add a pull-up resistor on it, unless your pin will never go to the high level unless your device have internal pull-up.

If you want to protect your PIC i/O from short, then use something like ~100-200 Ohm would work. In theory each I/O is capable to drive/sink 25mA... 5V/25mA=200 Ohms. Higher the current limiting + Faster your signal is, higher the chance to screw up your signal shape/edges/amplitude, higher the chance to have issue.


As you don't use Shiftin, you don't need to worry about SO