#include <Arduino.h>

#define DEBUG true           //set to true for debug output, false for no debug output
#define DS if(DEBUG)Serial   // DS = Debug Serial

hw_timer_t *gateTimer = NULL;

int dimmerLevel = 0;

#define GATE 45
#define SCALEFACTOR 32 //  ((80 MHZ / 80 prescale) / 120 hz) / 256
#define ZERO_CROSS_PIN 46

void IRAM_ATTR Zero_Cross_Interrupt()
{
  if (dimmerLevel > 0)
  {
    digitalWrite(GATE, HIGH);
    timerAlarmWrite(gateTimer, SCALEFACTOR*dimmerLevel, true);
    timerAlarmEnable( gateTimer);
    timerWrite( gateTimer, 0);
    timerStart( gateTimer);
  }
  else
  {
    digitalWrite(GATE, LOW);
  }

  delayMicroseconds(400); // debounce zero-crossing
}

void IRAM_ATTR onGateTimer()
{
  digitalWrite(GATE, LOW );
  timerStop( gateTimer);
}



//***************************************************************************
void setup(){
  #if DEBUG
  Serial.begin(115200);
  while (!Serial){}
  #endif

  pinMode(ZERO_CROSS_PIN,INPUT_PULLUP);
  pinMode(GATE,OUTPUT);

  digitalWrite( GATE, LOW);
  
  attachInterrupt(ZERO_CROSS_PIN, Zero_Cross_Interrupt, FALLING);

  gateTimer = timerBegin(0, 80, true);
  timerAttachInterrupt(gateTimer, &onGateTimer, true);
  timerAlarmWrite(gateTimer, 4000, true);

}


void loop(){

  dimmerLevel = 0;
  for (int i=0;i<250;i++)
  {
    dimmerLevel++;
    delay(100);
  }
  for (int i=250;i>0;i--)
  {
    dimmerLevel--;
    delay(100);
  }

}