/* modified from orignal noted below code now */

# include <avr/sleep.h>

const byte interruptPin = 2;
const byte LEDPin = 6;

void flashLed(int count, int t) {
  for (byte i = 0; i < count; i++) {
    digitalWrite(LEDPin, HIGH);
    delay(t);
    digitalWrite(LEDPin, LOW);
    delay(t);
  }
}

void setup() {
  Serial.begin(57600);
  Serial.println("hello sleep world!\n");

  pinMode(LEDPin, OUTPUT);
  pinMode(interruptPin, INPUT_PULLUP);
}

void loop() {
  flashLed(2, 500);
  Serial.println("AWAKE");
  flashLed(10, 100);

  Serial.println("Going to sleep in 3 sec");
  flashLed(3, 500);
  
  Going_To_Sleep();

  Serial.print("woke up and fully ");
}

byte didAnything = 0;   // did we even use the ISR?

void Going_To_Sleep() {
  sleep_enable();//Enabling sleep mode
  
  attachInterrupt(digitalPinToInterrupt(interruptPin), wakeUp, LOW );

  set_sleep_mode(SLEEP_MODE_PWR_SAVE);
  
  digitalWrite(LEDPin, LOW); //turning LED off
 
  sleep_cpu();//activating sleep mode

  Serial.print("just woke up!  ");//next line of code executed after the interrupt
  Serial.println(didAnything ? " did ISR" : " didn't ISR");//next line of code executed after the interrupt
  didAnything = 0;
 
  digitalWrite(LEDPin, HIGH); //turning LED on
  delay(500);
}

void wakeUp() {
  didAnything = 1;
  Serial.println("\nInterrupt Fired...");//Print message to serial monitor
  sleep_disable();//Disable sleep mode
  detachInterrupt(digitalPinToInterrupt(interruptPin)); //Removes the interrupt from interruptPin;
}

/**
   Author:Ab Kurk    version: 1.0     date: 24/01/2018
   Description:    This sketch is part of the beginners guide to putting your Arduino to sleep
   tutorial. It is to demonstrate how to put your arduino into deep sleep and how to wake it up.
   Link To Tutorial http://www.thearduinomakerman.info/blog/2018/1/24/guide-to-arduino-sleep-mode

   INFO
   Micro, Leonardo, other 32u4-based boards support interrupts on pins 0, 1, 2, 3, 7
   Sleep modes For the Atmega328P (Nick Gammon http://www.gammon.com.au/power
   SLEEP_MODE_IDLE: 15 mA  //does not stay asleep
   SLEEP_MODE_ADC: 6.5 mA //does not stay asleep
   SLEEP_MODE_PWR_SAVE: 1.62 mA  //wont wake up
   SLEEP_MODE_EXT_STANDBY: 1.62 mA //wont wake up
   SLEEP_MODE_STANDBY : 0.84 mA //wont wake up
   SLEEP_MODE_PWR_DOWN : 0.36 mA  //wont wake up
*/