Arduino的教學02-控制 LED 燈光亮度與PWM

一、教學目標：控制LE燈亮度(呼吸燈)

http://coopermaa2nd.blogspot.tw/2010/12/arduino-lab3-led.html

http://yehnan.blogspot.tw/2012/02/arduino_16.html

二、接線圖

三、程式碼

int brightness = 0;    // how bright the LED is
int fadeAmount = 5;    // how many points to fade the LED by

void setup()  { 
  // declare pin 9 to be an output:
  pinMode(9, OUTPUT);
} 

void loop()  { 
  // set the brightness of pin 9:
  analogWrite(9, brightness);    

  // change the brightness for next time through the loop:
  brightness = brightness + fadeAmount;

  // reverse the direction of the fading at the ends of the fade: 
  if (brightness == 0 || brightness == 255) {
    fadeAmount = -fadeAmount ; 
  }     
  // wait for 30 milliseconds to see the dimming effect    
  delay(30);                            
}

四、作業練習 1.如何讓呼吸燈的變化頻率快一點？