I have a project which needs to sleep most of the time, and when a button gets pressed, it does its thing which is producing a fading sound wave (using interrupts) until it's time to sleep again.

The goal is to reduce work load on the battery so the item can last as long as possible.

#include <avr/sleep.h>
void setup(){
  /*givePin! This is the pin that will spark the waking up!*/
  /*changes to timers registers*/
void loop(){
  ampCurrentlyOn = digitalRead(givePin);
  ampPulse =  (ampCurrentlyOn && !ampPreviouslyOn) * 255     //Reset 
           + !(ampCurrentlyOn && !ampPreviouslyOn) * ampPulse//Same
           -   bool(ampPulse);  //Decay
  ampPreviouslyOn = ampCurrentlyOn;
  if(!ampPulse){//Once that value reaches 0 time to GOTO bed;
    /*This! Is this what I need to do?*/

Am I doing in the right direction? Could any pin work? How do I get the chip to understand a pin set to digital HIGH to wake up from nap time?

Thank you!

  • 2
    you search for something like attachInterrupt(digitalPinToInterrupt(givePin), [](){}, FALLING);? givePin must be pin capable of external interrupt.(pin 2 or 3 on Uno/Nano) ([](){} is empty anonymous function)
    – Juraj
    Commented Aug 30, 2020 at 14:58
  • 1
    You shouldn't call cli before sleep, or it will never wake up. I also think you need to call sleep_enable();.
    – Gerben
    Commented Aug 30, 2020 at 18:26
  • 2
    @Gerben: sleep_mode() takes care of calling sleep_enable(). Commented Aug 31, 2020 at 18:11


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