I am currently designing a PCB that should be used for connecting NES and SNES connectors to the GPIOs. The connectors, in turn, will be used for connecting NES or SNES gamepads. From the ouside it will look like this:
The PCB is supposed to replace the board that I used in >>this<< work. There the PCB really just replaced some wires.
The new PCB should contain some GPIO protection circuitry. Furthermore a momentary switch should be soldered onto the board. The controllers are driven with 3.3V and can be polled with just three data lines each. I used the Zener diode protection as explained >>here<< and my current PCB design of the new board looks like this:
I am not sure about some things here:
- Would you say that it is necessary for this application to have a protection for the GND and VCC pins as well? If so, what would you propose?
- Is this an appropriate protection for the case in which the controllers are disconnected while the RPi in switched on ("transients protection")?