CIPAD 36e leçon: 2e partie: Initiation au KeyPad 4x4 et gestion de mot de passe

Introduction

This tutorial provides a comprehensive guide to using a 4x4 keypad and managing passwords in your Arduino projects. It is particularly relevant for beginners looking to enhance their programming skills and learn how to interface with hardware components effectively.

Step 1: Understanding the 4x4 Keypad

• What is a 4x4 Keypad?

  • A 4x4 keypad consists of 16 buttons arranged in a grid format, allowing for easy input.

• Wiring the Keypad

  • Connect the keypad to your Arduino by following these pin assignments:
    • Row pins to Arduino digital pins (e.g., 2 to 5)
    • Column pins to another set of digital pins (e.g., 6 to 9)

• Practical Tip: Double-check your connections to avoid issues during programming.

Step 2: Installing Required Libraries

• Download Keypad Library
  • Use the Arduino IDE to install the Keypad library. Go to:
    • Sketch > Include Library > Manage Libraries
    • Search for "Keypad" and install the library developed by Mark Stanley and Alexander Brevig.

Step 3: Writing the Code

• Basic Code Structure

  • Start with including the necessary libraries:

    #include <Keypad.h>
    

• Define Keypad Layout

  • Set up the keypad layout using a character array:

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

• Define the Connections

  • Create an instance of the Keypad class:

    byte rowPins[ROWS] = {2, 3, 4, 5}; 
    byte colPins[COLS] = {6, 7, 8, 9}; 
    Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
    

• Implementing Password Functionality

  • Define a password and compare user input:

    String password = "1234"; // Set your desired password
    String inputPassword;
    
    void loop() {
      char key = keypad.getKey();
      if (key) {
        inputPassword += key; // Append key press to password string
      }
      if (inputPassword.length() == 4) {
        if (inputPassword == password) {
          // Password matched
        } else {
          // Password not matched
        }
        inputPassword = ""; // Reset input
      }
    }
    

Step 4: Testing the Setup

• Upload the Code

  • Connect your Arduino to the computer and upload the code.

• Testing the Keypad

  • Open the Serial Monitor to observe the input and check if the password functionality works as intended.

• Common Pitfalls

  • Ensure that the baud rate in the Serial Monitor matches the one set in your code (usually 9600).

Conclusion

In this tutorial, you've learned how to set up a 4x4 keypad and implement a simple password management system using Arduino. Key takeaways include understanding the wiring, installing libraries, writing essential code, and testing your setup.

For further exploration, consider adapting the password system to include features like password resets or incorporating additional security measures.