Now that we are using microcontrollers for driving all our controls and indicators, we need to define how their respective I/Os will be used. For that purpose, we’ve added a new sheet to our master spreadsheet. The first microcontroller unit (MCU) to be defined is the one installed on our CV board. It will require 32 I/Os for driving our 32 LEDs, and one for checking whether the portplate is open or closed (PPP, for portplate position). The latter will be implemented using a switch or some light sensor.