ESP32 - LED - Blink

This tutorial instructs you how to use esp32 to blink an LED. This is one of the first tutorials that beginers learn.

Hardware Used In This Tutorial

1×ESP-WROOM-32 Dev Module
1×Micro USB Cable
1×LED
1×220 ohm resistor
1×Breadboard
2×Jumper Wires
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Introduction to LED

LED Pinout

LED includes two pins:

  • Cathode(-) pin: connect this pin to GND (0V)
  • Anode(+) pin: is used to control LED's state
  • LED Pinout

How LED Works

After connecting the cathode(-) to GND:

  • If we connect VCC to the anode(+), LED is ON.
  • If we connect GND to the anode(+), LED is OFF.
  • How LED Works

In addition, if a PWM signal is generated to the anode(+), the LED's brightness is changed in proportion to the PWM duty cycle. See more detailed in ESP32 fade LED tutorial.

※ NOTE THAT:

  • Usually, A resistor is required to protect LED from burning. The resistor can be placed between the anode(+) and VCC or between the cathode(-) and GND. The resistance value depends on the LED's specification.
  • Some LEDs have a built-in resistor, so there is no need to use a resistor for them.

ESP32 - LED

The ESP32's digital output pin's voltage can be programmed to VCC or GND. By connecting the digital output pin to LED, we can programmatically control the LED's state.

Wiring Diagram between LED and ESP32

wiring diagram between esp32 led

This image is created using Fritzing. Click to enlarge image

How To Program

  • Configure an ESP32's pin to the digital output mode by using pinMode() function. For example, pin GIOP18:
pinMode(18, OUTPUT);
  • Program the pin to GND to turn OFF led by using digitalWrite() function:
digitalWrite(18, LOW);
  • Program the pin to VCC to turn ON led by using digitalWrite() function:
digitalWrite(18, HIGH);

ESP32 Code

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.
  • Copy the below code and paste it to Arduino IDE.
/* * 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-led-blink */ // the code in setup function runs only one time when ESP32 starts void setup() { // initialize digital pin GIOP18 as an output. pinMode(18, OUTPUT); } // the code in loop function is executed repeatedly infinitely void loop() { digitalWrite(18, HIGH); // turn the LED on delay(500); // wait for 500 milliseconds digitalWrite(18, LOW); // turn the LED off delay(500); // wait for 500 milliseconds }
  • Compile and upload code to ESP32 board by clicking Upload button on Arduino IDE
  • How to upload ESP32 code on Arduino IDE
  • See the result: The LED blinks one time per second.

Line-by-line Code Explanation

The above ESP32 code contains line-by-line explanation. Please read the comments in the code!

※ NOTE THAT:

The above code uses the delay(). This function blocks ESP32 from doing other tasks . To avoid blocking ESP32, see ESP32 blink without delay

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