 #include <LiquidCrystal.h>
 
-#define END_SENSOR A1
-#define START_SENSOR A2
+#define END_SENSOR A1 // sensor at start gate
+#define START_SENSOR A2 // sensor at finish line
 #define SENSOR_LOW 0
-#define SENSOR_HIGH 150 //250
-// sensor % is used
+
+// sensor pct is used
 // as a multiplier against the ambient
 // light
 #define SENSOR_PCT 0.8

void setup() {
  lcd.begin(16, 2);
  lcd.clear();
  pinMode(START_SENSOR, INPUT);
  pinMode(END_SENSOR, INPUT);
  Serial.begin(9600);      // open the serial port at 9600 bps:

    elapsed_time = endtime - starttime;

    // debounce finished sensor
    // probably not strictly necessary
    while (finished) {
      finished = sensor_tripped(END_SENSOR, SENSOR_LOW, sensor_high_end);
    }
