Basically three different methods.
1. A simple "brake on" switch in order to determine if the pedal has been depressed. This is to be implemented in the Bunderson solution. As the brake light switch is already integrated into the aftermarket pedal set and the installation of inline sensors into the braking system will only serve to weaken a system that requires extreme resiliency.
2. Pressure sensors.
Probably the best solution as it will give an accurate measurement of the required pressure to stop a vehicle. Cheap pressure sensors may be found in some trailer braking systems.
Requires one digital input or ADC input for reading pressure. Maybe two ADC channels for front and rear pressures, and a switch for the handbrake.
Bunderson is a bit of a weird beast as there are three pressure differentials. There are two separate circuits, one front and one rear. The rear circuit is then split into two at a cutting brake which gives me the ability to tractor style turn. (Bunderson loves to push) IE two front brakes on one circuit. And each rear brake individually controlled.
OK. So three ADC channels?
Again this is fully dependant on where the project goes in the future, and how much modification to the Genboard is required. We should as a matter of course attempt to present as many analog or digital channels as possible to the end user. I’m sure there will be applications for use for someone in the future. However the Bunderson only requires a simple switch for brake metering for at least the first year of datalogging, possibly forever!
3. Linea Potentiometer mounted on pedal will give a measurement of how far the pedal is depressed. However won't determine between boiling fluid and an increased need to stop.