/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/
#include <avr/sleep.h>
#include <MsTimer2.h>


const int TrigPin = 4;
const int EchoPin = 5;


const unsigned long TIME = 512;
const unsigned long TWOTIME = TIME*2;

// --------
// Wake up
// --------
int wakePin = 2;                 // pin used for waking up
int sleepStatus = 0;             // variable to store a request for sleep
int count = 0;                   // counter

// ----------
// Timer
// ----------

void flash() {
//   Serial.println("flash");
  static boolean output = HIGH;

  digitalWrite(13, output);
  
  //digitalWrite(wakePin, LOW);

  output = !output;

  sleepNow();
  
}

/******************************************************************/
 
void setup() {
   Serial.begin(9600);
  
  // Wakeup
  pinMode(wakePin, INPUT);

  /* Now it is time to enable an interrupt. In the function call 
   * attachInterrupt(A, B, C)
   * A   can be either 0 or 1 for interrupts on pin 2 or 3.   
   * 
   * B   Name of a function you want to execute while in interrupt A.
   *
   * C   Trigger mode of the interrupt pin. can be:
   *             LOW        a low level trigger
   *             CHANGE     a change in level trigger
   *             RISING     a rising edge of a level trigger
   *             FALLING    a falling edge of a level trigger
   *
   * In all but the IDLE sleep modes only LOW can be used.
   */

  attachInterrupt(0, wakeUpNow, LOW); // use interrupt 0 (pin 2) and run function
                                      // wakeUpNow when pin 2 gets LOW 
  
  
  pinMode(TrigPin, OUTPUT);
  pinMode(EchoPin, INPUT);


  //timer
  pinMode(13, OUTPUT);

  MsTimer2::set(5000, flash); // 500ms period
  MsTimer2::start();
  
}

void wakeUpNow()        // here the interrupt is handled after wakeup
{
  // execute code here after wake-up before returning to the loop() function
  // timers and code using timers (serial.print and more...) will not work here.
  // we don't really need to execute any special functions here, since we
  // just want the thing to wake up
//  Serial.println("Reveil");

}

void sleepNow()         // here we put the arduino to sleep
{
    /* Now is the time to set the sleep mode. In the Atmega8 datasheet
     * http://www.atmel.com/dyn/resources/prod_documents/doc2486.pdf on page 35
     * there is a list of sleep modes which explains which clocks and 
     * wake up sources are available in which sleep mode.
     *
     * In the avr/sleep.h file, the call names of these sleep modes are to be found:
     *
     * The 5 different modes are:
     *     SLEEP_MODE_IDLE         -the least power savings 
     *     SLEEP_MODE_ADC
     *     SLEEP_MODE_PWR_SAVE
     *     SLEEP_MODE_STANDBY
     *     SLEEP_MODE_PWR_DOWN     -the most power savings
     *SLEEP_MODE_IDLE: 15 mA
      SLEEP_MODE_ADC: 6.5 mA
      SLEEP_MODE_PWR_SAVE: 1.62 mA
      SLEEP_MODE_EXT_STANDBY: 1.62 mA
      SLEEP_MODE_STANDBY : 0.84 mA
      SLEEP_MODE_PWR_DOWN : 0.36 mA
     * For now, we want as much power savings as possible, so we 
     * choose the according 
     * sleep mode: SLEEP_MODE_PWR_DOWN
     * 
     */  
    set_sleep_mode(SLEEP_MODE_PWR_DOWN);   // sleep mode is set here

    sleep_enable();          // enables the sleep bit in the mcucr register
                             // so sleep is possible. just a safety pin 

    /* Now it is time to enable an interrupt. We do it here so an 
     * accidentally pushed interrupt button doesn't interrupt 
     * our running program. if you want to be able to run 
     * interrupt code besides the sleep function, place it in 
     * setup() for example.
     * 
     * In the function call attachInterrupt(A, B, C)
     * A   can be either 0 or 1 for interrupts on pin 2 or 3.   
     * 
     * B   Name of a function you want to execute at interrupt for A.
     *
     * C   Trigger mode of the interrupt pin. can be:
     *             LOW        a low level triggers
     *             CHANGE     a change in level triggers
     *             RISING     a rising edge of a level triggers
     *             FALLING    a falling edge of a level triggers
     *
     * In all but the IDLE sleep modes only LOW can be used.
     */

    attachInterrupt(0,wakeUpNow, LOW); // use interrupt 0 (pin 2) and run function
                                       // wakeUpNow when pin 2 gets LOW 

    sleep_mode();            // here the device is actually put to sleep!!
                             // THE PROGRAM CONTINUES FROM HERE AFTER WAKING UP

    sleep_disable();         // first thing after waking from sleep:
                             // disable sleep...
    detachInterrupt(0);      // disables interrupt 0 on pin 2 so the 
                             // wakeUpNow code will not be executed 
                             // during normal running time.
  
}

void loop ()  {
  

  //sleepNow();     // sleep function called here
  
  
}