Dimmer_isr_loop

#include "PinChangeInterrupt.h"
#include "TinyWireS.h"

#define I2C_SLAVE_ADDR  2
int AC_LOAD = 3;
int ZCD_Pin = 1;
int dimming = 128;
int Speed[3] = {90, 50, 20};
int speedValue;
bool fan;
bool isr_;

void setup() {
  pinMode(AC_LOAD, OUTPUT);
  TinyWireS.begin(I2C_SLAVE_ADDR);
  TinyWireS.onReceive(receiveEvent);
  pinMode(ZCD_Pin, INPUT_PULLUP);
}


void zero_crosss_int()  //function to be fired at the zero crossing to dim the light
{
  isr_ = true;
}

void receiveEvent(uint8_t howMany)
{
  byte byteRcvd = 0;
  if (TinyWireS.available()) {
    byteRcvd = TinyWireS.receive();     // get the byte from master

    if (byteRcvd == '0') {
      fan = false;
      detachPinChangeInterrupt(digitalPinToPCINT(ZCD_Pin));
      digitalWrite(AC_LOAD, LOW);
    }
    if (byteRcvd == '1') {
      fan = true;
      speedValue = Speed[0];    //90
      attachPCINT(digitalPinToPCINT(ZCD_Pin), zero_crosss_int, FALLING);
    }
    if (byteRcvd == '2') {
      fan = true;
      speedValue = Speed[1];   //50
      attachPCINT(digitalPinToPCINT(ZCD_Pin), zero_crosss_int, FALLING);
    }
    if (byteRcvd == '3') {
      fan = true;
      speedValue = Speed[2];  //20
      attachPCINT(digitalPinToPCINT(ZCD_Pin), zero_crosss_int, FALLING);
    }
    dimming = speedValue;
  }
}

void loop() {
  if (isr_) {
    long int dimtime;
    dimtime = (75 * dimming);  // For 60Hz =>65
    delayMicroseconds(dimtime);    // Wait till firing the TRIAC
    digitalWrite(AC_LOAD, HIGH);   // Fire the TRIAC
    delayMicroseconds(100);         // triac On propogation delay  // (for 60Hz use 8.33) Some Triacs need a longer period
    digitalWrite(AC_LOAD, LOW);    // No longer trigger the TRIAC (the next zero crossing will swith it off) TRIAC
  }
}