[SOLVED]Difference between INPUT_PULLUP and an external pull down resistor?

B1ueB1aze:
or if something is expecting on to mean HIGH, correct?

The question of HIGH = ON (or whatever) is based on however you write your code to interpret it. Consider:

  • switch_open = TRUE;
  • switch_closed = TRUE;
    Well, you can test for the switch being open or closed. It's more a question of how, functionally, you're thinking about the way your circuit operates.