Arduino Sleep Mode

[last updated: 2022-02-28]
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• from: https://thekurks.net/blog/2018/1/24/guide-to-arduino-sleep-mode
  • Power down mode (SLEEP_MODE_PWR_DOWN).
  • #include // this AVR library contains methods to control sleep modes
    #define interruptPin 2 // this pin will be used to wake up out of sleep mode

    
    void setup () {
    Serial.begin .. why??
    pinMode (13, OUTPUT); // onboard LED to indicate sleep mode
    pinMode (interruptPin, INPUT_PULLUP);
    digitalWrite (13, HIGH); // awake at start, will be turned off when asleep

  • void loop ()
    sleep_enable();
    attachInterrupt (0, wakeUp, LOW); // attacvhes interrupt to pin 2 ???
    set_sleep_mode (SLEEP_MODE_POWER_DOWN);
    digitalWrite(13, LOW); // turn off "awake" led
    delay(1000); // wait for LED to turn off
    sleep_cpu(); // activate sleep mode

    // this is first line that will be executed when it wakes up
    digitalWrite(13, HIGH); // turn on "awake" led

• see also:
  • https://www.arduino.cc/en/Reference/LowPowerDeepSleep
  • https://github.com/rocketscream/Low-Power
  • https://www.reddit.com/r/arduino/comments/axrlq7/sleep_mode_on_an_atmega...
  • http://cdn.sparkfun.com/datasheets/Dev/Arduino/Boards/ATMega32U4.pdf
  • http://www.gammon.com.au/power
  • https://medesign.seas.upenn.edu/index.php/Guides/MaEvArM-pcint
  • https://www.arduino.cc/reference/en/language/functions/external-interrup...

• addendum from:
  https://arduino.stackexchange.com/questions/61659/how-ro-re-enable-32u4-...

  There is a method to re-start the USB, but it only works if the USB has been properly stopped - and the method that is supposed to do that is empty.
  This is a little sketch that works on my Leonardo:

  #include

  void setup() {
  }

  void loop() {
  USBCON = 0;
  LowPower.powerDown(SLEEP_8S, ADC_OFF, BOD_OFF);

  USBDevice.attach();

  pinMode(13, OUTPUT);
  digitalWrite(13, HIGH);

  delay(10000);
  digitalWrite(13, LOW);
  }
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  It disables the USB (USBCON = 0;), sleeps for 8 seconds, then starts the USB up again from scratch (USBDevice.attach();). 10 seconds later it sleeps again.
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