ESP32 - RGB LED

This tutorial instructs you how to control RGB LED to emit any color using ESP32.

Hardware Used In This Tutorial

1	×	ESP-WROOM-32 Dev Module
1	×	Micro USB Cable
1	×	RGB LED
1	×	(Alternative) RGB LED Module
1	×	Breadboard
1	×	Jumper Wires
1	×	(Optional) DC Power Jack
1	×	(Optional) ESP32 Screw Terminal Adapter

Or you can buy the following sensor kit:

DIYables Sensor Kit 30 types, 69 units

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Introduction to RGB LED

The RGB LED can emit any colors by mixing the 3 basic colors red, green and blue. A single RGB LED is composed of 3 LEDs: red, green and blue. These three LEDs are packed into a single case so that it looks like a single LED.

RGB LED Pinout

RGB LED includes four pins:

R (red) pin: is to control the red color element
G (green) pin: is to control the green color element
B (blue) pin: is to control the blue color element
Common (Cathode-) pin: connect this pin to GND (0V)

To hook up RGB LED to ESP32, we gotta add current-limiting resistors. This can complicate the wiring. Luckily, we can use an RGB LED module that comes with pre-built current-limiting resistors.

RGB LED Module also includes four pins:

Common (Cathode-) pin: needs to be connected to GND (0V)
R (red): pin is used to control red
G (green): pin is used to control green
B (blue): pin is used to control blue

※ NOTE THAT:

According to the common pin, there are two types of LED: common anode and common cathode. This tutorial uses a common cathode LED.

How RGB LED works

In term of physics, a color is a combination of three color elements: Red (R), Green (G) and Blue (B). Each color element's value range is from 0 to 255. The combination of values of three color elements create 256 x 256 x 256 colors in total.

If we generate PWM signals to R, G, B pins, the RGB LED diplays a color corresponding to the PWM duty cycle values. By changing the duty cycle of PWM signals (from 0 to 255), the RGB LED can display any color. The color values of Red (R), Grean (G) and Blue (B) correspond to PWM duty cycle on R, G and B pins , respectively.

Wiring Diagram between RGB LED and ESP32

Wiring diagram between ESP32 and RGB LED

This image is created using Fritzing. Click to enlarge image

Wiring diagram between ESP32 and RGB LED module

This image is created using Fritzing. Click to enlarge image

How To Control RGB LED

Let's assume that we want to display #00979D color on RGB LED, we can do the following step:

Find the color code. Tips:

You can pick up color code you want from the color picker
If you want to use color in an image, use online Colors From Image tool

Convert color code to R, G, B values using the tool from w3school. Take note these values. in this case: R = 0, G = 151, B = 157

Define ESP32 pins that connects to R, G, and B pins. For example:

#define PIN_RED 23 // GPIO23 #define PIN_GREEN 22 // GPIO22 #define PIN_BLUE 21 // GPIO21

Configure these ESP32 pins to the output mode

pinMode(PIN_RED, OUTPUT); pinMode(PIN_GREEN, OUTPUT); pinMode(PIN_BLUE, OUTPUT);

Control LED to emit that color (#00979D → R = 0, G = 151, B = 157)

analogWrite(PIN_RED, 0); analogWrite(PIN_GREEN, 151); analogWrite(PIN_BLUE, 157);

ESP32 - RGB LED Example Code

The below code changes color of LED among following colors in sequence:

#00C9CC (R = 0, G = 201, B = 204)
#F7788A (R = 247, G = 120, B = 138)
#34A853 (R = 52, G = 168, B = 83)

/* * This ESP32 code is created by esp32io.com * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-rgb-led */ #define PIN_RED 23 // GPIO23 #define PIN_GREEN 22 // GPIO22 #define PIN_BLUE 21 // GPIO21 void setup() { pinMode(PIN_RED, OUTPUT); pinMode(PIN_GREEN, OUTPUT); pinMode(PIN_BLUE, OUTPUT); } void loop() { // color code #00C9CC (R = 0, G = 201, B = 204) analogWrite(PIN_RED, 0); analogWrite(PIN_GREEN, 201); analogWrite(PIN_BLUE, 204); delay(1000); // keep the color 1 second // color code #F7788A (R = 247, G = 120, B = 138) analogWrite(PIN_RED, 247); analogWrite(PIN_GREEN, 120); analogWrite(PIN_BLUE, 138); delay(1000); // keep the color 1 second // color code #34A853 (R = 52, G = 168, B = 83) analogWrite(PIN_RED, 52); analogWrite(PIN_GREEN, 168); analogWrite(PIN_BLUE, 83); delay(1000); // keep the color 1 second }

When using many colors, we could shorten the code by creating a function:

/* * This ESP32 code is created by esp32io.com * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-rgb-led */ #define PIN_RED 23 // GPIO23 #define PIN_GREEN 22 // GPIO22 #define PIN_BLUE 21 // GPIO21 void setup() { pinMode(PIN_RED, OUTPUT); pinMode(PIN_GREEN, OUTPUT); pinMode(PIN_BLUE, OUTPUT); } void loop() { // color code #00C9CC (R = 0, G = 201, B = 204) setColor(0, 201, 204); delay(1000); // keep the color 1 second // color code #F7788A (R = 247, G = 120, B = 138) setColor(247, 120, 138); delay(1000); // keep the color 1 second // color code #34A853 (R = 52, G = 168, B = 83) setColor(52, 168, 83); delay(1000); // keep the color 1 second } void setColor(int R, int G, int B) { analogWrite(PIN_RED, R); analogWrite(PIN_GREEN, G); analogWrite(PIN_BLUE, B); }

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