CIPAD 33: 3 approches pour contrôler le rétro-éclairage des afficheurs LCD standards

Introduction

This tutorial focuses on three approaches to control the backlighting of standard LCD displays using Arduino. It is designed for beginners and will guide you through analog, digital, and mixed control methods. Understanding these techniques will enhance your projects by allowing you to adjust display brightness effectively.

Step 1: Understanding Analog Control

Analog control involves using a variable voltage to adjust the brightness of the LCD backlight.

• Components Needed:

  • Arduino board
  • LCD display
  • Potentiometer (variable resistor)
  • Connecting wires

• Wiring Instructions:

  1. Connect the potentiometer to the Arduino:
     • One end to 5V.
     • The other end to GND.
     • The middle pin to an analog input pin (e.g., A0).
  2. Connect the LCD backlight to a PWM-capable output pin (e.g., pin 9).

• Code Example:

  const int potPin = A0; // Potentiometer connected to A0
  const int ledPin = 9;  // LCD backlight connected to pin 9
  
  void setup() {
    pinMode(ledPin, OUTPUT);
  }
  
  void loop() {
    int potValue = analogRead(potPin); // Read potentiometer value
    int brightness = map(potValue, 0, 1023, 0, 255); // Map to brightness
    analogWrite(ledPin, brightness); // Set brightness of backlight
    delay(100); // Small delay for stability
  }
  

Step 2: Implementing Digital Control

Digital control uses binary signals to turn the backlight on or off.

• Components Needed:

  • Arduino board
  • LCD display
  • Push button
  • Resistor (10kΩ for pull-down)

• Wiring Instructions:

  1. Connect the push button to a digital input pin (e.g., pin 2) and GND.
  2. Connect the LCD backlight to a digital output pin (e.g., pin 9).

• Code Example:

  const int buttonPin = 2; // Push button connected to pin 2
  const int ledPin = 9;    // LCD backlight connected to pin 9
  int buttonState = 0;
  
  void setup() {
    pinMode(buttonPin, INPUT);
    pinMode(ledPin, OUTPUT);
  }
  
  void loop() {
    buttonState = digitalRead(buttonPin); // Read button state
    if (buttonState == HIGH) {
      digitalWrite(ledPin, HIGH); // Turn on backlight
    } else {
      digitalWrite(ledPin, LOW); // Turn off backlight
    }
    delay(100); // Small delay for stability
  }
  

Step 3: Using Mixed Control

Mixed control combines both analog and digital methods, allowing for more nuanced control of the backlight.

• Components Needed:

  • Arduino board
  • LCD display
  • Potentiometer
  • Push button

• Wiring Instructions:

  • Use the wiring from Steps 1 and 2, ensuring both the potentiometer and button are connected to their respective pins.

• Code Example:

  const int potPin = A0; // Potentiometer connected to A0
  const int buttonPin = 2; // Push button connected to pin 2
  const int ledPin = 9;    // LCD backlight connected to pin 9
  int buttonState = 0;
  
  void setup() {
    pinMode(potPin, INPUT);
    pinMode(buttonPin, INPUT);
    pinMode(ledPin, OUTPUT);
  }
  
  void loop() {
    buttonState = digitalRead(buttonPin); // Read button state
    if (buttonState == HIGH) {
      int potValue = analogRead(potPin); // Read potentiometer value
      int brightness = map(potValue, 0, 1023, 0, 255); // Map to brightness
      analogWrite(ledPin, brightness); // Set brightness of backlight
    } else {
      digitalWrite(ledPin, LOW); // Turn off backlight
    }
    delay(100); // Small delay for stability
  }
  

Conclusion

In this tutorial, we explored three approaches to control the backlighting of LCD displays using Arduino: analog, digital, and mixed control. Each method has its unique advantages and applications, making them useful for different project requirements. Experiment with these techniques to enhance your Arduino projects and improve your understanding of electronics. Happy coding!