1.水哥学习arduino系列之按键开关lcd背光

quan 编辑于2025-03-06 20:33arduino学习

第一次学习arduino硬件中断，做了个开关，可以用按键控制lcd背光。用的是i2c的接口，所以调用了LiquidCrystal_I2C.h的库。我这里用了i2c接在后面，四个接口由上到下分别是：GND,VCC,SDA,SCL。分别插在arduinoUNO板上。我这里的lcd电压是3.3v的，如果您的lcd是5v的，就接在旁边的5v的接口上，否则会损坏lcd和arduinoUNO板。

硬件

源码

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>
#define BUTTON_PIN 2

int target_backlightState = false;
int current_backlightState = false;
LiquidCrystal_I2C lcd(0x27,16,2);  // set the LCD address to 0x27 for a 16 chars and 2 line display

void setup()
{
  pinMode(BUTTON_PIN,INPUT_PULLUP);
  lcd.init();                      // initialize the lcd 
// Print a message to the LCD.
  lcd.setCursor(0,0);
  lcd.print("Welcome to the");
  lcd.setCursor(0,1);
  lcd.print("Arduino world!");
  attachInterrupt(0, press_isr, FALLING);

}

void press_isr(){
    target_backlightState = !target_backlightState;
}
 
void loop()
{ 
    if (target_backlightState != current_backlightState) {
          if(current_backlightState){
            lcd.noBacklight();
            current_backlightState = false;
            }//if
          else{
            lcd.backlight();
            current_backlightState = true;
            }//else
      }//if
}//loop

这个代码已经完成了开关lcd背光的功能，但测试了一下，偶尔没有响应，原来是按键抖动，就查了一下按键消抖，安装了bounce2库来解决按键抖动的问题。

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>
#include <Bounce2.h>
#define BUTTON_PIN 2
Bounce2::Button button = Bounce2::Button();

int target_backlightState = false;
int current_backlightState = false;
LiquidCrystal_I2C lcd(0x27,16,2);  // set the LCD address to 0x27 for a 16 chars and 2 line display

void setup()
{
  button.attach( BUTTON_PIN, INPUT ); // USE EXTERNAL PULL-UP
  button.interval(5); // DEBOUNCE INTERVAL IN MILLISECONDS
  button.setPressedState(LOW); // INDICATE THAT THE LOW STATE CORRESPONDS TO PHYSICALLY PRESSING THE BUTTON  
  pinMode(BUTTON_PIN,INPUT_PULLUP);
  lcd.init();                      // initialize the lcd 
// Print a message to the LCD.
  lcd.setCursor(0,0);
  lcd.print("Welcome to the");
  lcd.setCursor(0,1);
  lcd.print("Arduino world!");
  attachInterrupt(0, press_isr, FALLING);

}

void press_isr(){
    target_backlightState = !target_backlightState;
}
 
void loop()
{ 
      /*if (target_backlightState != current_backlightState) {
          if(current_backlightState){
            lcd.noBacklight();
            current_backlightState = false;
            }//if
          else{
            lcd.backlight();
            current_backlightState = true;
            }//else
      }//if
*/
    button.update();
    if(button.pressed()){
        if(current_backlightState){
            lcd.noBacklight();
            current_backlightState = false;
         }//if
        else{
            lcd.backlight();
            current_backlightState = true;
        }//else
    }//if
}//loop

因为lcd默认的背光太亮，而且软件无法调节背光亮度，我就把开启背光的跳线帽换成了一个1k欧的电阻。