 
 struct clock_sync clock;
 
-// Interupt handlers for laser and screen photodiodes
+// Interrupt handler for laser photodiode
 void irq_laser(void) {
   laser.t = time_us;
   // May need to remove the 'not' if not using internal pullup resistor

  pinMode(G_PIN, INPUT);

  attachInterrupt(PD_LASER_PIN, irq_laser, CHANGE);
  attachInterrupt(PD_SCREEN_PIN, irq_screen, CHANGE);

  // Turn on the red LED, will be turned off once time is synced
  led_state = HIGH;

    }
  }

  // Probe screen
  if (screen.probe) {
    int v = analogRead(PD_SCREEN_PIN);
    if ((screen.value == LOW && v > SCREEN_THRESH_HIGH) || (screen.value != LOW && v < SCREEN_THRESH_LOW)) {
      screen.t = time_us;
      screen.count++;
      led_state = !led_state;
      screen.value = !screen.value;
    }
  }

  // Send out any triggers with autosend and pending data
  for (int i = 0; i < TRIGGER_COUNT; i++) {

