#define PHOTO_PIN 7

void setup() {
  Serial.begin(115200);
  pinMode(PHOTO_PIN, INPUT);
  Serial.print("In Time");
  Serial.print("\t");
  Serial.println("Out Time");
  //Serial.println("In Time\tOut Time");
}

void loop() {
  if (digitalRead(PHOTO_PIN) == LOW) {
    long t_in = micros();
    while (digitalRead(PHOTO_PIN) == LOW);
    long t_out = micros();
    Serial.print(t_in);
    Serial.print("\t");
    Serial.println(t_out);
    //Serial.println(String(t_in) + "\t" + String(t_out));
  }
}