Identify GPIOs to use on the Onion
For Inputs develop an interface suitable for the signals to read, keep in mind Onion only reads digital inputs
For outputs identify if PWM is needed, beware of maximum current to handle, relay may be more convenient than solid state devices.
Initialize inputs and outputs in the bash script (in this case) at the begining.
Debug reading inputs and setting an output
Dive under the in-panel fishing for the correct signals to read and activate
Connect experimental I/Os by twisting the wires until the set up is confirmed to work.
Solder and tie wires, relays, transistors so that components won't rattle or fly during usage
For specific Open Doors, Close Doors, Starter functions. Put the Bash scripts under /www/cgi-bin/* and call them from any browser with 192.168.3.1/cgi-bin/Script.cgi
Debug with a terminal and ssh