Mega 2560 coding issues

Projects Programming
1

Hello. Before I begin, Yes, I have read and searched the forums for my answer and I'm still baffled.
In the code below, when I start the program I'm trying to get LED1 to illuminate using a photoresistor which is the visual input for me to depress the pushbutton. It doesn't work for whatever reason. I have looked at it and tried several different coding configurations for LED 3 but it still doesn't work. The rest of the program works as designed. What am I overlooking? Thanks for any help

#include<LiquidCrystal.h>
#include<Servo.h>

LiquidCrystal lcd(8, 9, 10, 11, 12, 13);
Servo startingGate;

const byte buttonPin = 3; //starting line button for "GO"
const byte servoPin = 2;
const byte finishSensor1Pin = A0;
const byte finishSensor2Pin = A1;

const int darkThreshold = 500;
int LED1 = 7;   //lane 1 win light
int LED2 = 6;   //lane 2 win light
int LED3 = 43;  //prestage light
int finishSensor1;
int finishSensor2;
boolean finishFlag = false;
long startTime;
long stopTime;
float raceTime;

void setup()
{
 
  Serial.begin(9600);  // initializes servo for starting line
  pinMode(buttonPin, INPUT_PULLUP);
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);
  startingGate.attach(servoPin, 1000, 2000);
  startingGate.write(0);

  lcd.begin(16, 2);
  lcd.clear();
  lcd.print("Drag Strip Timer");  //initial display Line 1 on lcd
  lcd.setCursor(0, 1);
  lcd.print("Push to start!");  //inital display Line 2 on lcd

  while (digitalRead(buttonPin) == HIGH)
  {
  }

  lcd.clear();
  lcd.print("Go!");  //displayed after race start
  digitalWrite(LED1, HIGH);  //turns on win light upon reset
  digitalWrite(LED2, HIGH);  //turns on win light upon reset
  digitalWrite(LED3, LOW);
  startingGate.write(180);
  startTime = millis();
}

void loop()
{
  //read the finish sensors at the same time
  finishSensor1 = analogRead(finishSensor1Pin);
  finishSensor2 = analogRead(finishSensor2Pin);
  if (finishFlag == false)
  {
    //car #1 crosses first
    if ((finishSensor1 < darkThreshold) && (finishSensor2 > darkThreshold))
    {
      stopTime = millis();
      raceTime = stopTime - startTime;
      finishFlag = true;
      digitalWrite(LED1, LOW);
      lcd.clear();
      lcd.print("Winner Lane #1");  //displayed if lane 1 photeresistor changes state before lane 2
      lcd.setCursor(0, 1);
      lcd.print("Time: ");
      lcd.print(raceTime / 1000, 3);
    }
    //car #2 crosses first
    else if ((finishSensor2 < darkThreshold) && (finishSensor1 > darkThreshold))
    {
      stopTime = millis();
      raceTime = stopTime - startTime;  //formula used to determine elapsed time
      finishFlag = true;
      digitalWrite(LED2, LOW); 
      lcd.clear();
      lcd.print("Winner Lane #2");   //displayed if lane 2 photeresistor changes state before lane 1
      lcd.setCursor(0, 1);
      lcd.print("ET: ");  //displays winning elapsed time
      lcd.print(raceTime / 1000, 3);
    }
  }
}
2

Please explain the above ?

3

That is the command to "start" the timer.

4 

  finishSensor1 = analogRead(finishSensor1Pin);
  finishSensor2 = analogRead(finishSensor2Pin);

Print these values to see what they start at and go to when the light changes.

BTW, Show us a good schematic of your circuit.
Show us a good image of your ‘actual’ wiring.

5

I’m not sure how to do this. I assume this is to determine the output status of the pin on the board?

6 
Serial.println(finishSensor1);

Serial.println(finishSensor2);

To confirm what is actually being read.

There is an icon with an up arrow in the posting menu.

Use it to upload the schematic and actual wiring images.

“ I have looked at it and tried several different coding configurations for LED 3 but it still doesn't work”

Don’t see a digitalWrite(LED3, HIGH); anywhere.

BTW
Run the simple Blink sketch to see if the LED3 is wired properly.

7

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