I'm working on an all in 1 controller and would like to incorporate a pendent for jogging and such. The controller will be running GRBL and hopefully sport an SD reader. With that said I plan to use 2 Arduino 328p IC's, one to run GRBL and the other to control the SD side of things. So to the case at point, I was thinking for the jog, could I not build a pendent that with a push of a button would set the step/direction pins of said driver high or low instead of doing it software based. That would be a lot easier but I fear of back feeding to the Arduino's pins when the pendent sends the 5v to step/dir. Would say a diode in line with the Arduino pins prevent this issue?