ESP32 - LED - Fade
This tutorial instructs you how to use ESP32 to fade a LED. We also learn how to fade-in/fade-out LED without using delay() function
Hardware Used In This Tutorial
|1||×||ESP-WROOM-32 Dev Module|
|1||×||Micro USB Cable|
|1||×||220 ohm resistor|
Introduction to LED
LED includes two pins:
- Cathode(-) pin: connect this pin to GND (0V)
- Anode(+) pin: is used to control LED's state
How LED Works
After connecting the cathode(-) to GND:
- If We connect GND to the anode(+), LED is OFF.
- If We connect VCC to the anode(+), LED is ON.
- If We generate a PWM signal to the anode(+) pin, the LED's brightness is in proportion to PWM duty cycle. PWM duty cycle varies from 0 to 255. The bigger the PWM duty cycle is, the brighter the LED is.
- If PWM value is 0, it is equivalent to GND ⇒ LED is OFF
- If PWM value is 255, it is equivalent to VCC ⇒ LED is ON at the highest brightness.
※ NOTE THAT:
Usually, it requires a resistor to protect LED from burning. The resistance's value depends on the LED's specification.
ESP32 - fade LED
The ESP32's digital output pins can be programmed to generate PWM signal. By connecting LED's anode(+) pin to an ESP32's pin, LED's cathode(-) to GND, and then programming ESP32 to change the duty cytle of PWM, we We can fade LED.
Wiring Diagram between LED and ESP32
This image is created using Fritzing. Click to enlarge image
How To Program
- Configure an ESP32's pin as a digital output pin by using pinMode() function. For example, pin GIOP18:
- Set brightness of LED by generating PWM signal with corresponding duty cycle by using analogWrite() function:
Where brightness is a value from 0 to 255.
ESP32 Code - Simple Fade Example
- If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE.
- Do the wiring as above image.
- Connect the ESP32 board to your PC via a micro USB cable
- Open Arduino IDE on your PC.
- Select the right ESP32 board (e.g. ESP32 Dev Module) and COM port.
- Copy the below code and paste it to Arduino IDE.
- Compile and upload code to ESP32 board by clicking Upload button on Arduino IDE
- See the brightness of LED
Line-by-line Code Explanation
The above ESP32 code contains line-by-line explanation. Please read the comments in the code!
How to fade-in LED in a period without using delay()
How to fade-out LED in a period without using delay()
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