I wrote a number of microcontroller GPIO libraries (essentially set pin direction, set pin, read pin, read pin as analog input). I'd like to create an automated test to verify that my library indeed does the correct things with the correct pins. Doing this by hand is tedious and not something I want to do after each change.
Has anyone designed a hardware software combination to automate this? For instance, some resistor DA converter connected to the output pins, output to an A/D pin, seqeunce the output pins and verify that the correct voltage is read from the AD pin. But that leaves the digital inputs untested.