arusr:
There a several modes to attach an interrupt according to Arduio.cc:attachInterrupt(0, pin2_isr, XXXX);
LOW to trigger the interrupt whenever the pin is low,
CHANGE to trigger the interrupt whenever the pin changes value
RISING to trigger when the pin goes from low to high,
FALLING for when the pin goes from high to low.How come HIGH isn't an option?
Because RISING is a better choice, meaning the interrupt will be generated when the signal changes from LOW to HIGH.