I recently switched from Arduino Uno to a Sparkfun Arduino Pro Micro due to the size. The attached code works fine on an Uno with 2 foot switches attached without using any pull-up resistors. When I try this code on a Pro Mico it will only work with one foot switch attached. It doesn’t matter which foot switch or which pin I attach to. As soon as I connect the second foot switch even without pressing it the voltage of higher number goes low. I tried adding 2200 ohm resistors to VCC to overcome the problem assuming that the internal INPUT_PULLUP was not working but that did not change anything. I was originally using pins 2 and 3 but move to 3 and 4 to see if that made any difference and it did not.
Does anyone have any experience working with this board? Are there any substantial differences that change the way input works on the Pro Micro?
Any thoughts or suggestions would be greatly appreciated.
IceboxArduinoIo_USB_INT.cc (2.7 KB)