// Pins connected to 74HC595
const int CLOCK_PIN = 27;
const int LATCH_PIN = 26;
const int DATA_PIN = 25;

// Column GPIOs
const int colPins[8] = {21, 19, 18, 17, 16, 4, 12, 14};

// Array to keep track of key states
bool keyStates[3][8] = {false};

void setRow(int row) {
    // Offset by +1 because ROW 0 is connected to Q1 and not Q0
    uint8_t rowValue = ~(1 << (row + 1));
    shiftOut(DATA_PIN, CLOCK_PIN, MSBFIRST, rowValue);

    // Latch to transfer the data to output pins
    digitalWrite(LATCH_PIN, LOW);
    digitalWrite(LATCH_PIN, HIGH);

    // Small delay to allow the shift register output to stabilize
    delayMicroseconds(10);
}

void setup() {
    // Initialize serial for debugging
    Serial.begin(115200);

    // Initialize column pins
    for (int i = 0; i < 8; i++) {
        pinMode(colPins[i], INPUT_PULLUP);
    }

    // Initialize 74HC595 control pins
    pinMode(CLOCK_PIN, OUTPUT);
    pinMode(LATCH_PIN, OUTPUT);
    pinMode(DATA_PIN, OUTPUT);
}

void loop() {
    for (int row = 0; row < 3; row++) {
        // Set the current row to LOW
        setRow(row);
        
        // Check each column for a key press
        for (int col = 0; col < 8; col++) {
            int currentState = digitalRead(colPins[col]);
            if (currentState == LOW && !keyStates[row][col]) {
                // Button was just pressed
                keyStates[row][col] = true;
                Serial.printf("COL %d, ROW %d: Pressed\n", col + 1, row + 1);
            } else if (currentState == HIGH && keyStates[row][col]) {
                // Button was just released
                keyStates[row][col] = false;
                Serial.printf("COL %d, ROW %d: Released\n", col + 1, row + 1);
            }
        }
    }
    delay(200);  // Adjust as needed for scanning speed
}