Uses timer 3,4 and 5 to create pulse train for driving 3 stepper motors
Motor 0:
timer 3
step pin = pin A6
dir pin = pin A5
EN pin = pin A4
Motor 1
timer 4
step pin = pin D12
dir pin = pin D11
EN pin = pin D10
Motor 3
timer 5
step pin = pin A0
dir pin = pin A2
EN pin = pin A1