Arduino Power Counter

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

#ifndef cbi
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#endif
#ifndef sbi
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#endif


/*
#define LANG_ELECTRICITY 'E'
#define MESG_ELEC_CURRENT 'c'
typedef struct {
    char lang;
    char mesg;
    double power;
    double elapsedkWh;
} Packet_t;

*/

#define SRAM __attribute__((section(".noinit")))

//Number of pulses, used to measure energy.
long pulseCount = 0;
//Used to measure power.
unsigned long pulseTime,lastTime;

//power and energy
double power, elapsedkWh;

//Number of pulses per wh - found or set on the meter.
int ppwh = 1; //1000 pulses/kwh = 1 pulse per wh

#define sleepmode 1

void setup()
{
  Serial.begin(115200);

// KWH interrupt attached to IRQ 1  = pin3
  attachInterrupt(0, onPulse, RISING);

  cbi( SMCR,SE );      // sleep enable, power down mode
  cbi( SMCR,SM0 );     // power down mode
  sbi( SMCR,SM1 );     // power down mode
  cbi( SMCR,SM2 );     // power down mode
}



void loop()
{
  //-------------------------------------------------------------
  // 1) Enter sleep mode
  //-------------------------------------------------------------
#if sleepmode
/*
 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
     *
 */

 cbi(ADCSRA,ADEN);    // switch Analog to Digital converter OFF

  set_sleep_mode(SLEEP_MODE_PWR_DOWN);
//  cli();
  sleep_enable();
  sleep_mode();
  sleep_bod_disable();
  sei();
  sleep_cpu();

// The arduino is now sleeping...

 //-------------------------------------------------------------
  // 2) Program will resume from here on interrupt
  //-------------------------------------------------------------

  sleep_disable();
 sbi(ADCSRA,ADEN);    // switch Analog to Digitalconverter ON
 Serial.println('P');
Serial.println(millis(),3);
   delay(10);
Serial.println(millis(),3);
   delay(20);
Serial.println(millis(),3);
   delay(10);
Serial.println(millis(),3);
   delay(10);
#endif

}


// The interrupt routine
void onPulse()
{


//used to measure time between pulses.
  lastTime = pulseTime;
  pulseTime= micros();

//pulseCounter
  pulseCount++;

//Calculate power
  power = (3600000000.0 / (pulseTime - lastTime))/ppwh;

  //Find kwh elapsed
  elapsedkWh = (1.0*pulseCount/(ppwh*1000)); //multiply by 1000 to pulses per wh to kwh convert wh to kwh

//Print the values.
  Serial.print("W:");
  Serial.print(power,4);
  Serial.print(" kWh:");
  Serial.print(elapsedkWh,3);
  Serial.print(" C:");
  Serial.print(pulseCount,4);
  Serial.print(" LT:");
  Serial.print(lastTime,4);
  Serial.print(" PT:");
  Serial.println(pulseTime,4);





}