Fading
This example 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 and with different ratio between on and off time.
Hardware Required
- Arduino or Genuino board
- LED
- 220 ohm resistor
- hook-up wires
- breadboard
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
In this example two loops are executed one after the other to increase and then decrease the value of the output on pin 9.
/*
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
This example code is in the public domain.
http://www.arduino.cc/en/Tutorial/Fading
*/
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);
}
}
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
This example code is in the public domain.
http://www.arduino.cc/en/Tutorial/Fading
*/
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);
}
}
See Also:
- for()
- analogWrite()
- delay()
- AnalogInOutSerial - Read an analog input pin, map the result, and then use that data to dim or brighten an LED.
- AnalogInput - Use a potentiometer to control the blinking of an LED.
- AnalogWriteMega - Fade 12 LEDs on and o¬ff, one by one, using an Arduino or Genuino Mega board.
- Calibration - Define a maximum and minimum for expected analog sensor values.
- Smoothing - Smooth multiple readings of an analog input.
Last revision 2015/07/29 by SM
