如何使用Arduino UNO和按钮在电路上闪烁LED？

Question

如何使用Arduino UNO和按钮在电路上闪烁LED？

3

    /*
  Button

 Turns on and off a light emitting diode(LED) connected to digital  
 pin 13, when pressing a pushbutton attached to pin 2. 


 The circuit:
 * LED attached from pin 13 to ground 
 * pushbutton attached to pin 2 from +5V
 * 10K resistor attached to pin 2 from ground

 * Note: on most Arduinos there is already an LED on the board
 attached to pin 13.


 created 2005
 by DojoDave <http://www.0j0.org>
 modified 30 Aug 2011
 by Tom Igoe

 This example code is in the public domain.

 http://www.arduino.cc/en/Tutorial/Button
 */

// set pin numbers:
const int buttonPin = 2;     // the number of the pushbutton pin
const int led =  11;      // the number of the LED pin

// variables will change:
int buttonState = 0;         // variable for reading the pushbutton status
int buttonHistory = 0;        //Counting variable for button being pressed

void setup() {
  // initialize the LED pin as an output:
  pinMode(led, OUTPUT);      
  // initialize the pushbutton pin as an input:
  pinMode(buttonPin, INPUT);     
}

void loop(){
  // read the state of the pushbutton value:
  buttonState = digitalRead(buttonPin);
  if (buttonState == HIGH){
    buttonState++;
  }

  // check if the pushbutton is pressed.
  // if it is, the buttonState is HIGH:
    if (buttonHistory >= 0 && buttonState >= 0) {  
      // turn LED on:;
      int x = x + (.1*255);
      analogWrite(led, x);  

    }
    else if (buttonState == LOW){
      analogWrite(led, 0);
    }

    if (buttonState == 11){
      buttonState = 0;
    }
    buttonHistory = buttonState;
}

以上一部分代码来自Arduino网站，但我还做了一些修改。

上面是我的代码。我的目标是在非焊接面包板上使用电阻器制作LED灯，在我按下该面包板上的按钮时点亮。它已经连接好了，我可以让LED灯亮起来，但并不会在我按下按钮时发生任何变化。我希望每次按下按钮后LED灯的亮度增加10％，然后当其达到最大亮度时，在下一次按下按钮时关闭。现在的问题是LED灯一直亮着，按下按钮也没有任何反应。

- David

我必须点赞这个："relaxen und watchen das blinkenlights"。 - Sergey Kalinichenko

1个回答

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- J.A.I.L. · Accepted Answer

你必须将LED连接到Arduino的PWM输出之一。

PWM输出可以设置为0至255的值，这意味着与该值成比例的时间将设置输出电流，并且其余时间将保持在0V。

请查看Arduino官方网站上的以下示例以淡入淡出LED。

你还应该使用map函数，因为它易于映射代码中的值。

至于你的代码，你可以尝试这个（我没有编译它，所以请原谅任何错误）：

// Read the state of the pushbutton value, and update the fade LED value:
buttonState = digitalRead(buttonPin);
if (buttonState == HIGH){
    // buttonState++; Probably this was the main bug in your code.
    buttonHistory++;
}

// We are cycling buttonHistory, not buttonState
if (buttonHistory == 11){
    buttonHistory = 0;
}

//if (buttonHistory >= 0 && buttonState >= 0) {
  // Turn LED on at desired intensity:;
  int x = map(buttonHistory, 0, 10, 0, 255); // Similar to doing x=.1*255*buttonHistory
  analogWrite(led, x);

//}
// REDUNDANT:
//else if (buttonState == LOW){
//  analogWrite(led, 0);
//}

你还应该考虑在循环之间添加delay()，否则LED的亮度更新速度太快了，你几乎察觉不到它（你会太快地调用digitalRead(buttonPin);）。一个好的位置可以在`analogWrite()`之后（感谢@mike的建议）：

analogWrite(led, x);
delay(500);