Random button presses

[er_name_not_found]

@ribbonman

unsigned long previousMillis;

should be
unsigned long previousMillis = 0;

@ribbonman

previousMillis = millis();

should be
previousMillis += 50;
As that is the timer window you need to maintain.

I don't think that would effect debounce though.

I think the issue is between val, old_val, and buttonstate.