2.Controlling LEDs with a Keypad and Arduino

 Controlling LEDs with a Keypad and Arduino

Components Needed:

1. Arduino board
2. 4x4 or 4x3 Keypad
3. LEDs (e.g., 3 LEDs)
4. Resistors (e.g., 220Ω for each LED)
5. Jumper wires
6. Breadboard (optional)

Connections:

1. Keypad: Connect the keypad pins to digital pins on your Arduino (e.g., rows to pins 9, 8, 7, 6 and columns to pins 5, 4, 3, 2).
2. LEDs: Connect the LEDs to digital pins (e.g., LED1 to pin 13, LED2 to pin 12, LED3 to pin 11). Don’t forget to add a current-limiting resistor in series with each LED.

Example Code:

C++ Code

#include <Keypad.h>

const byte ROWS = 4; // Number of rows
const byte COLS = 4; // Number of columns
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

byte rowPins[ROWS] = {9, 8, 7, 6};    // Connect to row pins of keypad
byte colPins[COLS] = {5, 4, 3, 2};     // Connect to column pins of keypad

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

// Define LED pins
const int LED1 = 13;
const int LED2 = 12;
const int LED3 = 11;

void setup() {
  // Set LED pins as outputs
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);
  Serial.begin(9600);
}

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

  if (key) {
    Serial.println(key);

    // Control LEDs based on key press
    switch (key) {
      case '1':
        digitalWrite(LED1, HIGH);  // Turn LED1 on
        break;
      case '2':
        digitalWrite(LED2, HIGH);  // Turn LED2 on
        break;
      case '3':
        digitalWrite(LED3, HIGH);  // Turn LED3 on
        break;
      case '4':
        digitalWrite(LED1, LOW);   // Turn LED1 off
        break;
      case '5':
        digitalWrite(LED2, LOW);   // Turn LED2 off
        break;
      case '6':
        digitalWrite(LED3, LOW);   // Turn LED3 off
        break;
      default:
        break;
    }
  }
}

Explanation:

1. Library Import: The Keypad library is included for interfacing with the keypad.
2. Define Rows and Columns: Set the number of rows and columns of the keypad.
3. Key Mapping and Pin Assignments: Assign the keypad pins and map the keys.
4. LED Pins Setup: Define and set up LED pins as outputs.
5. Loop Logic:
   • Use keypad.getKey() to detect key presses.
   • Depending on the key pressed, turn on or off specific LEDs:
     • Pressing '1', '2', or '3' turns on LED1, LED2, or LED3, respectively.
     • Pressing '4', '5', or '6' turns off LED1, LED2, or LED3, respectively.

Tips:

• You can expand the code to use more keys for different functions.
• Ensure your keypad and LED wiring are correct to avoid short circuits.