ESP32 - Blink multiple LED

This tutorial instructs you how to how to program ESP32 to blink multiple LED at the same time without using delay function.

Hardware Used In This Tutorial

1	×	ESP-WROOM-32 Dev Module
1	×	USB Cable Type-C
1	×	LED
1	×	220 ohm resistor
1	×	Breadboard
1	×	Jumper Wires
1	×	(Optional) DC Power Jack
1	×	(Recommended) ESP32 Screw Terminal Adapter

Or you can buy the following sensor kits:

1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	DIYables Sensor Kit (18 sensors/displays)

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Introduction to LED

We have specific a tutorial about LED. The tutorial contains detailed information and step-by-step instructions about hardware pinout, working principle, wiring connection to ESP32, ESP32 code... Learn more about them at the following link:

ESP32 - LED tutorial

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

If you're unfamiliar with how to supply power to the ESP32 and other components, you can find guidance in the following tutorial: How to Power ESP32.

ESP32 Code - Blink Multiple LEDs

To blink multiple LEDs, we cannot use the delay() function. Instead, we need to use the millis() function and manage the timestamps .

Managing timestamps while blinking multiple LEDs can be challenging for beginners. Thankfully, the ezLED library simplifies the process of blinking multiple LEDs by internally managing timestamps. This eliminates the need for users to handle timestamp management when utilizing this library. Additionally, you can enhance code clarity and brevity by employing an array of LEDs.

/* * 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-blink-multiple-led */ #include <ezLED.h> // ezLED library #define PIN_LED_1 16 // The ESP32 pin GPIO16 connected to LED 1 #define PIN_LED_2 17 // The ESP32 pin GPIO17 connected to LED 2 #define PIN_LED_3 18 // The ESP32 pin GPIO18 connected to LED 3 ezLED led1(PIN_LED_1); // create ezLED object that attach to pin PIN_LED_1 ezLED led2(PIN_LED_2); // create ezLED object that attach to pin PIN_LED_2 ezLED led3(PIN_LED_3); // create ezLED object that attach to pin PIN_LED_3 void setup() { Serial.begin(9600); led1.blink(500, 500); // 500ms ON, 500ms OFF, blink immediately led2.blink(200, 800); // 200ms ON, 800ms OFF, blink immediately led3.blink(200, 200); // 200ms ON, 200ms OFF, blink immediately } void loop() { led1.loop(); // MUST call the led1.loop() function in loop() led2.loop(); // MUST call the led2.loop() function in loop() led3.loop(); // MUST call the led3.loop() function in loop() // DO SOMETHING HERE }

Quick Instructions

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.
Click to the Libraries icon on the left bar of the Arduino IDE.
Search “ezLED”, then find the led library by ArduinoGetStarted
Click Install button to install ezLED library.

Copy the above code and paste it to Arduino IDE.
Compile and upload code to ESP32 board by clicking Upload button on Arduino IDE

Check out the status of LED

ESP32 Code - Blink Multiple LEDs by using array

We can optimize the above code by using an array of LEDs. The below code uses the array to manage LED objects.

/* * 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-blink-multiple-led */ #include <ezLED.h> // ezLED library #define NUM_LED 3 // three LEDs #define PIN_LED_1 16 // The ESP32 pin GPIO16 connected to LED 1 #define PIN_LED_2 17 // The ESP32 pin GPIO17 connected to LED 2 #define PIN_LED_3 18 // The ESP32 pin GPIO18 connected to LED 3 ezLED ledArray[NUM_LED] = { ezLED(PIN_LED_1), // create ezLED object that attach to pin PIN_LED_1 ezLED(PIN_LED_2), // create ezLED object that attach to pin PIN_LED_2 ezLED(PIN_LED_3) // create ezLED object that attach to pin PIN_LED_3 }; void setup() { Serial.begin(9600); ledArray[0].blink(500, 500); // 500ms ON, 500ms OFF, blink immediately ledArray[1].blink(200, 800); // 200ms ON, 800ms OFF, blink immediately ledArray[2].blink(200, 200); // 200ms ON, 200ms OFF, blink immediately } void loop() { for (int i = 0; i < NUM_LED; i++) ledArray[i].loop(); // MUST call the led.loop() function in loop() // DO SOMETHING HERE }

For the flexible blink, please refer to other functions of the ezLED library

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