We Interrupt This Broadcast…

TL;DR (nice ref)

When writing an Interrupt Service Routine (ISR):

• Keep it short
• Don’t use delay ()
• Don’t do serial prints
• Make variables shared with the main code volatile
• Variables shared with main code may need to be protected by “critical sections” (see below)
• Don’t try to turn interrupts off or on

INPUT or INPUT_PULLUP

Analog Comparator Interrupt

More than 2 pin interrupts

• “pin change” type interrupts.
  • interrupts on the Arduino Uno (Nick Gammon)
• Multiple pin change interrupt
  • Pin Change Interrupts If you choose your interrupt pins carefully you can have up to 5 pins that each have their own interrupt handler. After that you then have to start sharing a handler and you have to add some extra code to figure out which pin caused the interrupt.