I’m not familiar with the “vending machine” protocol he’s talking about, but it’s entirely reasonable that it has certain timing requirements. Usually the way y

I’m not familiar with the “vending machine” protocol he’s talking about, but it’s entirely reasonable that it has certain timing requirements. Usually the way you interface with these is by having a dedicated HW block to talk the protocol, or by bit banging. The former wouldn’t be supported on RPi because it’s obscure, the latter requires tight GPIO timing control that is difficult to guarantee on a non-real-time system like the RPi usually runs.