用按钮控制pwm

Question

我对arduino很陌生，我一直试图用按钮来控制pwm。我的任务是，当按下不同的按钮(按钮1: 25%、按钮2: 50%、按钮3 : 75%和没有按下按钮时)时，将pin 3的PWM值更改为不同的值，并打印出pin 3中的高值长度。但当我不按任何按钮时，它仍然会打印出一些奇怪的数字(我希望它会打印出0)，当我按下任何按钮时，值不会改变(大约1595-1605)。知道怎么修吗？当我尝试运行它的时候，视频，https://drive.google.com/file/d/16lE8LDmHdlz0SbHj0AGGMQ8nNEcT8rIT/view?usp=sharing

//
int button1 = 8;
int LED1 = 2;
int button2 = 11;
int LED2 = 4;
int button3 = 12;
int LED3 = 7;
int pwm3 = 3;
int pwm3V;
unsigned long duration;
void setup()
{
 pinMode(2, OUTPUT);
 pinMode(8, INPUT);
 pinMode(4, OUTPUT);
 pinMode(11, INPUT);
 pinMode(7, OUTPUT);
 pinMode(12, INPUT);
 pinMode(3, OUTPUT);
 Serial.begin(9600);
}

void loop()
{
 if (digitalRead(button1)== HIGH)//Press Button 1   
     {
       digitalWrite(LED1, HIGH);  
       pwm3V = 64;//pwm value 25%
     }
 if (digitalRead(button1)== LOW)// Unpress Button 1
     {
       digitalWrite(LED1, LOW);
       pwm3V = 0;//pwm value

     }
 if (digitalRead(button2)== HIGH)//Press Button 2
     {
       digitalWrite(LED2, HIGH);
       pwm3V = 64*2;//pwm value 50%
     }
 if (digitalRead(button2)== LOW)// Unpress Button 2
     {
      digitalWrite(LED2, LOW);
       pwm3V = 0;//pwm value

     }
 if (digitalRead(button3)== HIGH)// Press Button 3
     {
       digitalWrite(LED3, HIGH);
       pwm3V = 64*3;//pwm value 75%
     }
 if (digitalRead(button3)== LOW)// Unpress Button 3
     {
       digitalWrite(LED3, LOW);
       pwm3V = 0;//pwm value
     }
 analogWrite(pwm3, pwm3V); //set pwm value
 duration = pulseIn(pwm3, HIGH);
 Serial.print(duration); //print lenght of HIGH
       
} ``` 

Answer 1

变量pwm3V的值将始终是0，除非在正确的时间按下button3；问题在于控制结构。由于在按钮的电路图中使用了拉出电阻，当按下按钮时，在Arduino板上读取一个低信号。

在下面开发的解决方案中，我以您的源代码为基础，但是我做了大量的编辑。通过将按钮和引脚定义为一个系列，我使事情变得更简单。我检查了引脚是否低级别，以检查按钮按下状态。我使用loopControl变量设计了一种控制机制，这样在按下按钮后，在迭代中就不会清除输出。

int buttonPins[] = {8, 11, 12}, ledPins[] = {2, 4, 7}, pwmPin = 3;
size_t size = sizeof(buttonPins)/sizeof(buttonPins[0]);
int pwmOutputValue;
unsigned long duration, loopControl;

void setup(){
    for(size_t i = 0 ; i < size ; ++i){
        pinMode(buttonPins[i], INPUT);
        pinMode(ledPins[i], OUTPUT);
    }
    pinMode(pwmPin, OUTPUT);
    Serial.begin(9600);
}

int readButtons(){    
    for(size_t index = 0 ; index < size ; ++index)
        if(digitalRead(buttonPins[index]) == LOW)
            return index;
    return -1;
}

void updatePWMValue(){
    analogWrite(pwmOutputValue, pwmPin);
    duration = pulseIn(pwmOutputValue, HIGH);
    Serial.print(duration);
}

void loop(){
    int result = readButtons();
    
    if(result != -1){
        digitalWrite(result, HIGH);
        pwmOutputValue = 64 * result;
    }
    else {
      if(++loopControl > 100000){ // If this line is cancelled, the whole state is updated in the first cycle after the button is pressed.
        for(size_t i = 0 ; i < size ; ++i)
            digitalWrite(ledPins[i], LOW);

        pwmOutputValue = 0;
        loopControl = 0;
      }
    }
    updatePWMValue();
}