Question

我使用Arduino Uno并希望使用analogwrite方法同步点亮四个LED，但它们依次点亮。这是我的代码：

int brightness = 0;    
int fadeAmount = 5;    
boolean first = true;

void setup()  { 
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);
  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);
} 
void loop()  {

  if (first) {
    // these should iluminate synchronously
    analogWrite(2, brightness);
    analogWrite(3, brightness);
    analogWrite(4, brightness);
    analogWrite(5, brightness);
  } else {
    // these should iluminate synchronously
    analogWrite(6, brightness);
    analogWrite(7, brightness);
    analogWrite(8, brightness);
    analogWrite(9, brightness);
  }

  brightness = brightness + fadeAmount;

  if (brightness == 0 || brightness == 255) {
    fadeAmount = -fadeAmount ;
    if (brightness == 0) {
      reverseFirst();
    }
  }           

  delay(5);                            
}

void reverseFirst(){
  if (first) {
    first = false;
  } else {
    first = true;
  }
}

Answer 1

analogWrite仅在引脚3,5,6,9,10,11上有效工作，因为它们是PWM引脚。根据analogWrite源代码，所有其他引脚（如果与analogWrite一起使用）将默认返回到digitalWrite。

所以我怀疑你无法对其他引脚进行适当的模拟控制，这可能就是为什么不是所有引脚都同时开启的原因。

如果亮度对您很重要，那么我建议您只使用真正的PWM引脚。如果您需要超过六个引脚，那么您可以获得模拟扩展器芯片，或者更简单一些，您可以查看类似于＆＃34; ShiftPWM＆＃34;的内容。它是一个库，它使用移位寄存器有效地将脉冲移位到其输出，从而可以控制LED的亮度。请记住，它不再被维护。

如何用analogWrite同步照亮四个LED灯

1 个答案: