Fading a LED using PWM pins in Arduino - Ryzen Hunt

Fading effect with Arduino

Hello friends, in our previous post, we explained how to program an Arduino and also did a practical "Blinking an LED". In this post, we would learn how to create a fading effect using Arduino.

The fading effect is created when a LED brightens and fades gradually. We know that Arduino's digital pins can either be HIGH or LOW and to generate the fading effect we need to generate analog outputs (Note: Analog pins take analog input, they do not generate analog output.). Here we would use the concept of Pulse Width Modulation or PWM.

Pulse Width Modulation (PWM) is a trick to get analog output values with digital means. On the Arduino Board, pins marked with a " ~ " can be used to generate PWM output. Arduino UNO has 6 digital pins that can be used for PWM outputs (3, 5, 6, 9, 10, and 11). The PWM output lies between 0 and 2^8 - 1 or 0 and 255.

PWM works by modulating the duty cycle of a square wave ( a signal switched between on and off).

Now let's start our practical:

Components Required:

• Arduino UNO
• LED
• Resistance (220 kΩ)
• Breadboard
• Connecting wires

Circuit Diagram:

In the circuit given above, we connected the cathode pin of LED is connected to the GND pin and the Anode pin is connected to the digital pin 11 through a resistance. Now we need to write the code for this connection.

Source Code:

In previous Practical, we used the digitalWrite() keyword, but here we would use the analogWrite() keyword to generate analog output. The analogWrite() takes two parameters, first is the pin number and the second is the value that we need as output.

In our code, first, we declared a variable named " led " and assigned an integer value 11 that's our pin number connected to the LED and then we declared that variable " i " would have integer values. In our setup function, we defined the pin mode of the variable as OUTPUT and in the loop function, we used two for loops for iteration. The first for loop is to glow the LED and the second for loop is to fade the LED.

const int led = 11; int i; void setup() { pinMode(led, OUTPUT); } void loop() { for (i=0; i<255; i++) { analogWrite(led, i); delay(10); } for (i=255; i>0; i++) { analogWrite(led, i); delay(10); } }

Result:

After Uploading the Source code to the Board, We can see that the LED glows and fades gradually and creates a fading effect by changing its intensity.

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Also check:

• How to program Arduino and blink LED?
• What is Arduino and its various versions?

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