On boot up, if the Arduino finds a config file saved to the CD card it applies the last saved settings, if it cannot find a file it boots with factory settings, and creates a config file to save settings into. I
We would imagine that the switch circuit works like “when button pressed down, the circuit closes” and “button pressed again, the circuit breaks”. However, that is actually not the case. Buttons are usually made of mechanical elastic switches. When mechanical contacts are broken or closed (...