Are there any issues in using traditional switches with an Arduino?
The ATmega32U4 datasheet recommends not connecting (unused) pins directly to ground in case the pin gets configured as an output. VIL is defined as approximately 0.2VCC maximum, which with a pull-up of 20k means a pull-down of no more than about 4k7. With 5V this means approximately 200uA at most will be consumed by each switch when held on. As long as your PSU can accommodate all switches being on, there should be no problem with this configuration:







simulate this circuit &ndash; Schematic created using CircuitLab