#include <avr/sleep.h>
#include <avr/power.h>
#include <avr/wdt.h>
#include <EEPROM.h>

// Utility macros
#define adc_disable() (ADCSRA &= ~(1<<ADEN)) // disable ADC (before power-off)
#define adc_enable()  (ADCSRA |=  (1<<ADEN)) // re-enable ADC

#define BODS 7                     //BOD Sleep bit in MCUCR
#define BODSE 2                    //BOD Sleep enable bit in MCUCR

/** the current address in the EEPROM (i.e. which byte we're going to write to next) **/
int addr = 0;

#define LED_PIN (13)
#define USB_PIN (9)

volatile int f_wdt=1;



/***************************************************
 *  Name:        ISR(WDT_vect)
 *
 *  Returns:     Nothing.
 *
 *  Parameters:  None.
 *
 *  Description: Watchdog Interrupt Service. This
 *               is executed when watchdog timed out.
 *
 ***************************************************/
ISR(WDT_vect)
{
  if(f_wdt == 0)
  {
    f_wdt=1;
  }
//  else
//  {
//    Serial.println("WDT Overrun!!!");
//  }

}


/***************************************************
 *  Name:        enterSleep
 *
 *  Returns:     Nothing.
 *
 *  Parameters:  None.
 *
 *  Description: Enters the arduino into sleep mode.
 *
 ***************************************************/
void enterSleep(void)
{
  //set_sleep_mode(SLEEP_MODE_PWR_SAVE);   /* EDIT: could also use SLEEP_MODE_PWR_DOWN for lowest power consumption. */
  set_sleep_mode(SLEEP_MODE_PWR_DOWN);
  sleep_enable();
  
  /* Now enter sleep mode. */
  sleep_mode();
  
  /* The program will continue from here after the WDT timeout*/
  sleep_disable(); /* First thing to do is disable sleep. */
  
  /* Re-enable the peripherals. */
  power_all_enable();
}



/***************************************************
 *  Name:        setup
 *
 *  Returns:     Nothing.
 *
 *  Parameters:  None.
 *
 *  Description: Setup for the serial comms and the
 *                Watch dog timeout. 
 *
 ***************************************************/
void setup()
{
  //digitalWrite(0, LOW);
  //digitalWrite(1, LOW);
  
  pinMode(LED_PIN, OUTPUT);
  digitalWrite(LED_PIN, LOW);
  
  adc_disable();
  
  // turn bod off
  // bod consume 22 uA
   MCUCR |= (1<<BODS) | (1<<BODSE);
   MCUCR &= ~(1<<BODSE);  // must be done right before sleep  
  
  int val = EEPROM.read(addr);
  if(val==255){
    EEPROM.write(addr, 0);
  }
  //Serial.begin(9600);
  //Serial.println("Initialising...");
  //delay(100); //Allow for serial print to complete.

  //pinMode(LED_PIN,OUTPUT);

  /*** Setup the WDT ***/
  
  /* Clear the reset flag. */
  MCUSR &= ~(1<<WDRF);
  
  /* In order to change WDE or the prescaler, we need to
   * set WDCE (This will allow updates for 4 clock cycles).
   */
  WDTCSR |= (1<<WDCE) | (1<<WDE);

  /* set new watchdog timeout prescaler value */
  WDTCSR = 1<<WDP0 | 1<<WDP3; /* 8.0 seconds */
  
  /* Enable the WD interrupt (note no reset). */
  WDTCSR |= _BV(WDIE);
  
  //Serial.println("Initialisation complete.");
  //delay(100); //Allow for serial print to complete.
}


/***************************************************
 *  Name:        enterSleep
 *
 *  Returns:     Nothing.
 *
 *  Parameters:  None.
 *
 *  Description: Main application loop.
 *
 ***************************************************/
void loop()
{
  if(f_wdt == 1)
  {
    int val = EEPROM.read(addr);
    //int ret;
    /* Toggle the LED */
    //ret = digitalRead(LED_PIN);
    //digitalWrite(LED_PIN, !ret);

//    if(ret==HIGH){
//      digitalWrite(USB_PIN, HIGH);
//      delay(100);
//      digitalWrite(USB_PIN, LOW);
//    }

    val++;

    if(val>23){
      digitalWrite(USB_PIN, HIGH);
      delay(7000);
      digitalWrite(USB_PIN, LOW);
      EEPROM.write(addr, 0);
    }else{
      EEPROM.write(addr, val);
    }

    /* Don't forget to clear the flag. */
    f_wdt = 0;

    /* Re-enter sleep mode. */
    enterSleep();
  }
  else
  {
    /* Do nothing. */
  }
}