CIPAD 35: Partie 1: Initiation au pavé numérique (Keypad)

Introduction

This tutorial is designed to guide you through the basics of using a numeric keypad with Arduino, as introduced in the CIPAD series by Daniel Talbot. It aims to provide beginners with a clear understanding of how to integrate and program a keypad for various applications. By the end of this tutorial, you will have a working knowledge of how to set up and utilize a numeric keypad in your projects.

Step 1: Understand the Keypad Layout

Before starting with the hardware, familiarize yourself with the layout of the numeric keypad.

• A typical numeric keypad contains 16 keys, arranged in a 4x4 matrix:
  • Rows: 4 (1, 2, 3, A)
  • Columns: 4 (4, 5, 6, B)
  • Additional keys: 0, *, #, and C

Practical Tip

Take a moment to visualize how each key corresponds to its row and column. This understanding is crucial for programming the keypad effectively.

Step 2: Gather Required Components

To get started, ensure you have the following components:

• Arduino board (e.g., Arduino Uno)
• Numeric keypad module
• Jumper wires
• Breadboard (optional for easier connections)
• Resistors (if necessary for your specific keypad)

Practical Advice

Check the specifications of your keypad to determine if pull-up or pull-down resistors are needed for proper functioning.

Step 3: Wiring the Keypad

Connect the keypad to the Arduino according to the following wiring scheme:

1. Identify the Pins:

   • The keypad typically has 8 pins (4 for rows and 4 for columns).

2. Connect the Pins:

   • Connect the row pins of the keypad to digital pins on the Arduino (e.g., 2, 3, 4, 5).
   • Connect the column pins to another set of digital pins (e.g., 6, 7, 8, 9).

Example Wiring

Keypad Pin 1 (Row 1)  -> Arduino Pin 2
Keypad Pin 2 (Row 2)  -> Arduino Pin 3
Keypad Pin 3 (Row 3)  -> Arduino Pin 4
Keypad Pin 4 (Row 4)  -> Arduino Pin 5
Keypad Pin 5 (Col 1)  -> Arduino Pin 6
Keypad Pin 6 (Col 2)  -> Arduino Pin 7
Keypad Pin 7 (Col 3)  -> Arduino Pin 8
Keypad Pin 8 (Col 4)  -> Arduino Pin 9

Common Pitfall

Ensure that the connections are secure and that no wires are loose, as this can lead to unreliable readings.

Step 4: Install Required Libraries

To easily interact with the keypad, you will need to install the Keypad library:

1. Open the Arduino IDE.
2. Navigate to Sketch > Include Library > Manage Libraries.
3. Search for "Keypad" and install the library by Mark Stanley and Alexander Brevig.

Step 5: Write the Code

Now, write a simple sketch to read the keypad input:

#include <Keypad.h>

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'}
};

byte rowPins[ROWS] = {2, 3, 4, 5}; 
byte colPins[COLS] = {6, 7, 8, 9}; 

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

void setup() {
  Serial.begin(9600);
}

void loop() {
  char key = keypad.getKey();
  if (key) {
    Serial.println(key);
  }
}

Explanation

• The Keypad library simplifies the process of reading key presses.
• The code initializes the keypad and prints any pressed key to the Serial Monitor.

Step 6: Test Your Setup

• Upload the code to your Arduino.
• Open the Serial Monitor in the Arduino IDE (set to 9600 baud rate).
• Press various keys on the keypad and observe the output in the Serial Monitor.

Practical Tip

If no output appears, double-check your wiring and ensure the correct pins are set in the code.

Conclusion

In this tutorial, you learned how to set up a numeric keypad with Arduino, from understanding the layout to writing and testing the code. This foundational knowledge can be applied to various projects, such as creating a secure access system or a simple calculator. As a next step, consider experimenting with different applications or integrating other components to enhance your keypad project.