#include <Keypad.h>

const uint8_t ROWS = 4;
const uint8_t COLS = 4;
int aPin = 10; 
int bPin = 11; 
int cPin = 12; 
int dPin = 13; 
char keys[ROWS][COLS] = {
  { '1', '2', '3', 'A' },
  { '4', '5', '6', 'B' },
  { '7', '8', '9', 'C' },
  { '*', '0', '#', 'D' }
};

uint8_t colPins[COLS] = { 5, 4, 3, 2 }; // Pins connected to C1, C2, C3, C4
uint8_t rowPins[ROWS] = { 9, 8, 7, 6 }; // Pins connected to R1, R2, R3, R4

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

void setup() {
  pinMode(aPin, OUTPUT);
  pinMode(bPin, OUTPUT);
  pinMode(cPin, OUTPUT);
  pinMode(dPin, OUTPUT); 
}

void loop() {
  char key = keypad.getKey();

  if (key == 'A') {
    digitalWrite(aPin, HIGH ); 
    delay(200); 
  } else if (key == 'B') {
    digitalWrite(bPin, HIGH);
    delay(200);  
  } else if (key == 'C') {
    digitalWrite(cPin, HIGH);
    delay(200);  
  } else if (key == 'D') {
    digitalWrite(dPin, HIGH); 
    delay(200); 
  } else {
    digitalWrite(aPin, LOW); 
    digitalWrite(bPin, LOW);
    digitalWrite(cPin, LOW); 
    digitalWrite(dPin, LOW);  
  }
}