#define NUMELEMENTS(x) (sizeof(x) / sizeof(x[0]))

byte dataPin = 2;
byte clockPin = 3;
byte latchPin = 4;
byte outputEnablePin = 6;

// timing in microseconds
unsigned long timerInterval = 2000;
unsigned long previousMicros = 0;

uint8_t data = 0;

uint16_t pulseWidths[] = { 200, 400, 600, 800, 1000, 1200, 2000 };

void setup() {
  Serial.begin(115200);
  Serial.println(F("Software PWM"));

  pinMode(dataPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(latchPin, OUTPUT);
  pinMode(outputEnablePin, OUTPUT);
}

void loop() {
  unsigned long currentMicros = micros();

  if (currentMicros - previousMicros >= timerInterval) {
    previousMicros = currentMicros;
    for (int i = 0; i < NUMELEMENTS(pulseWidths); i++)
      if (pulseWidths[i] > 0) {
        data |= 1 << i;
      }
  } else {
    for (int i = 0; i <  NUMELEMENTS(pulseWidths); i++) {
      if (currentMicros - previousMicros >= pulseWidths[i]) {

        data &= ~(1 << i);
      }
    }
  }

  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, data << 1);
  digitalWrite(latchPin, HIGH);
}