Downloaded and installed the IO Pi library and tutorial code files..
Working through the IO Pi tutorials.
Learning is not neat. God this is fun! When a button connected on the left is pressed it causes a IO Pi HAT interrupt; which is connected to a Raspberry Pi GPIO pin (white wire on the right); causing a Raspberry Pi interrupt. The routine responding to that interrupt turns on and off an LED connected to an IO Pi HAT output pin. Proof of concept. Learned something today, now I can go to bed.
Shift to WiFi socket connection to Laptop (4) and serial connection to Arduino/base station (2). Learning curve strikes again.
Raspberry Pi can now 'speak' to the Arduino/Base Station! Bedtime.
Added the Python documentation. Need to make some manual changes to the file generated by the pydoc application. I don't want to include links to all the standard python library packages.
The laptop & Raspberry are "talking"! They don't like each other nor understand what's going on. But I broke the code.
Added the IO Pi interrupt voltage dividers and header to the Unicorn custom board.