Interrupt

#include <IRremote.h>
#define triacPulse A0
#define ZCD 2           // Zero Cross Detector
#define RECV_PIN 7      // IR Pin

IRrecv irrecv(RECV_PIN);
decode_results results;
unsigned long key_value = 0;
const byte ZCDinterruptPin = 2;
int x = 0;
void setup() {
  Serial.begin(9600);
  irrecv.enableIRIn();
  irrecv.blink13(false);
  pinMode(ZCD, INPUT_PULLUP);
  pinMode(triacPulse, OUTPUT);
}

void loop() {

  if (irrecv.decode(&results)) {
    if (results.value == 0XFFFFFFFF)
      results.value = key_value;

    if (results.value == 0x88C000C) {   // LOW
      detachInterrupt(digitalPinToInterrupt(ZCDinterruptPin));
      motorLOW();
    }
    if (results.value == 0x88C0084) {   // MED
      detachInterrupt(digitalPinToInterrupt(ZCDinterruptPin));
      motorMED();
    }
    if (results.value == 0x880834F) {   // HIGH
      detachInterrupt(digitalPinToInterrupt(ZCDinterruptPin));
      motorHIGH();
    }
    key_value = results.value;
    irrecv.resume();
  }
}

void motorLOW(){
    attachInterrupt(digitalPinToInterrupt(ZCDinterruptPin), acon, FALLING); // attach Interrupt at PIN2
    x = 6600;     // LOW
}
void motorMED(){
    attachInterrupt(digitalPinToInterrupt(ZCDinterruptPin), acon, FALLING); // attach Interrupt at PIN2
    x = 4866;     // MED
}
void motorHIGH(){
    attachInterrupt(digitalPinToInterrupt(ZCDinterruptPin), acon, FALLING); // attach Interrupt at PIN2
    x = 2533;     // HIGH
}

void acon()
{
//  detachInterrupt(digitalPinToInterrupt(ZCDinterruptPin));
  delayMicroseconds(x); // read AD0
  digitalWrite(triacPulse, HIGH);
  delayMicroseconds(50);  //delay 50 uSec on output pulse to turn on triac
  digitalWrite(triacPulse, LOW);
  detachInterrupt(digitalPinToInterrupt(ZCDinterruptPin));
}