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en:learing:examples:fading

Fading

Demonstrates the use of analog output (Pulse Width Modulation (PWM)) to fade an LED. PWM is a technique for getting an analog-like behavior from a digital output by switching it off and on very fast.

Circuit

An LED connected to digital output pin 9 through a 220-ohm resistor.

click the image to enlarge

Schematic

click the image to enlarge

image developed using Fritzing. For more circuit examples, see the Fritzing project page

Code

/*
 Fading
 
 This example shows how to fade an LED using the analogWrite() function.
 
 The circuit:
 * LED attached from digital pin 9 to ground.
 
 Created 1 Nov 2008
 By David A. Mellis
 modified 30 Aug 2011
 By Tom Igoe
 
 http://arduino.cc/en/Tutorial/Fading
 
 This example code is in the public domain.
 
 */
 
 
int ledPin = 9;    // LED connected to digital pin 9
 
void setup()  { 
  // nothing happens in setup 
} 
 
void loop()  { 
  // fade in from min to max in increments of 5 points:
  for(int fadeValue = 0 ; fadeValue <= 255; fadeValue +=5) { 
    // sets the value (range from 0 to 255):
    analogWrite(ledPin, fadeValue);         
    // wait for 30 milliseconds to see the dimming effect    
    delay(30);                            
  } 
 
  // fade out from max to min in increments of 5 points:
  for(int fadeValue = 255 ; fadeValue >= 0; fadeValue -=5) { 
    // sets the value (range from 0 to 255):
    analogWrite(ledPin, fadeValue);         
    // wait for 30 milliseconds to see the dimming effect    
    delay(30);                            
  } 
}
en/learing/examples/fading.txt · 最后更改: 2023/06/07 04:23 由 127.0.0.1