// Countdown Timer using Arduino Uno
// Connect common cathode 7-segment display to pins 2-9 (a-g) and 10-13 (digit selection)

const int a = 12;
const int b = 10;
const int c = 8;
const int d = 7;
const int e = 6;
const int f = 11;
const int g = 9;

int p = 0; // Placeholder for digit selection pin
int startStopReset = 13; // Button to start/reset the timer

long n = 60000; // Initial time (in milliseconds)
int x = 100; // Update interval (milliseconds)
int del = 55; // Delay for display refresh (microseconds)

void setup() {
    pinMode(a, OUTPUT);
    pinMode(b, OUTPUT);
    pinMode(c, OUTPUT);
    pinMode(d, OUTPUT);
    pinMode(e, OUTPUT);
    pinMode(f, OUTPUT);
    pinMode(g, OUTPUT);
    pinMode(p, OUTPUT);
    pinMode(startStopReset, INPUT);
    digitalWrite(startStopReset, HIGH);
}

void loop() {
    digitalWrite(p, HIGH);

    clearLEDs();
    pickDigit(1);
    pickNumber((n / x / 1000) % 10);
    delayMicroseconds(del);

    // Repeat for other digits (2, 3, 4)...

    n--; // Decrement time (you can use 'n++' for a stopwatch)

    if (digitalRead(startStopReset) == LOW) {
        n = 60000; // Reset time (change to your original start time)
    }
}

// Helper functions for displaying numbers (0-9) on the 7-segment display
// Implement these based on your display's pin configuration

void pickDigit(int x) {
    // Select the appropriate digit (1-4)
    // Set the corresponding digit pin LOW
    // Other digit pins should be HIGH
    // Example: digitalWrite(d1, LOW);
}

void pickNumber(int x) {
    // Display the number (0-9) on the 7-segment display
    // Implement this using individual segment pins (a-g)
    // Example: digitalWrite(a, HIGH); digitalWrite(b, LOW); ...
}

void clearLEDs() {
    // Turn off all segments (set all pins LOW)
}

// Implement functions zero(), one(), ..., nine() for each digit

// Remember to connect your 7-segment display properly!