#include <LiquidCrystal.h>

LiquidCrystal lcd(9, 10, 5, 4, 3, 2);
const int startButton = 11;
const int stopButton = 12;

unsigned long previousMillis = 0;
unsigned long interval = 10; // Update interval in milliseconds
float time = 0.0;
bool active = false;

unsigned long lastDebounceTimeStart = 0;  // Debounce timer for start button
unsigned long lastDebounceTimeStop = 0;   // Debounce timer for stop button
unsigned long debounceDelay = 50;         // Debounce delay

int lastButtonStateStart = HIGH;          // Previous state of the start button
int lastButtonStateStop = HIGH;           // Previous state of the stop button

void setup() {
  lcd.begin(16, 2);
  pinMode(startButton, INPUT_PULLUP);
  pinMode(stopButton, INPUT_PULLUP);
  lcd.print("Time: 0.00s");
}

void loop() {
  int readingStart = digitalRead(startButton);
  int readingStop = digitalRead(stopButton);

  // Start button debouncing
  if (readingStart != lastButtonStateStart) {
    lastDebounceTimeStart = millis();
  }
  if ((millis() - lastDebounceTimeStart) > debounceDelay) {
    if (readingStart == LOW && !active) {
      time = 0.0;  // Reset the timer
      active = true;
    }
  }
  lastButtonStateStart = readingStart;

  // Stop button debouncing
  if (readingStop != lastButtonStateStop) {
    lastDebounceTimeStop = millis();
  }
  if ((millis() - lastDebounceTimeStop) > debounceDelay) {
    if (readingStop == LOW && active) {
      active = false;
    }
  }
  lastButtonStateStop = readingStop;

  // Timer update
  if (active) {
    unsigned long currentMillis = millis();
    if (currentMillis - previousMillis >= interval) {
      previousMillis = currentMillis;
      time += interval / 1000.0;
      lcd.setCursor(0, 0);
      lcd.print("Time: ");
      lcd.print(time, 2);
      lcd.print("s  "); // Clear any trailing characters
    }
  }
}