// timing in microseconds
uint32_t timerInterval = 2000;
uint32_t onTime = 1500;
uint8_t percentage = 0;

// pins for the 74hc595 chip
byte dataPin = 2;
byte clockPin = 3;
byte latchPin = 4;
int outputEnablePin = 6;


// struct pulse to make things work 
struct Pulse
{
  uint32_t startTime;
  uint16_t pulseWidth;
  bool isOn;
};

Pulse Pulses [7] {
  {0, 35, false},
  {0, 70, false},
  {0, 105, false},
  {0, 140, false},
  {0, 175 , false},
  {0, 210, false},
  {0, 245, false}
}



void setup() {
  pinMode(dataPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(latchPin, OUTPUT);
  pinMode(outputEnablePin, OUTPUT);
}

void loop() {
 softPWM(percentage * timerInterval / 100);
}

/*
  softPWM
  Create the timebase
  In:
  pulse width
*/
void softPWM(uint16_t pulseWidth)
{
  static uint32_t startTime;
  static boolean refStatus = false;
  static bool trigger = false;

  if (micros() - startTime >= timerInterval)
  {
    startTime = micros();
    refStatus = !refStatus;
    trigger = true;
    digitalWrite(refPin, refStatus == true ? HIGH : LOW);

 }

  // if new period started
  if (trigger == true)
  {
    // create the pulse with the specified width
    trigger = pulse(pulseWidth);
  }
}




/*
  Create a pulse
  In:
  width of the pulse in microseconds
*/
bool pulse(uint16_t pulseWidth)
{
  static uint32_t startTime;
  static boolean isOn = false;

  if (pulseWidth == 0)
  {
    digitalWrite(pwmPin, LOW);
    return false;
  }

  if (isOn == false)
  {
    digitalWrite(pwmPin, HIGH);
    isOn = true;
    startTime = micros();

    return true;
  }

  if (micros() - startTime >= pulseWidth)
  {
    //startTime = micros();
    digitalWrite(pwmPin, LOW);
    isOn = false;

    return false;
  }
}