ESP32 PWM with Arduino IDE (Analog Output)

In this tutorial we’ll show you how to generate PWM signals with the ESP32 using Arduino IDE. As an example we’ll build a simple circuit that dims an LED using the LED PWM controller of the ESP32. We’ll also show you how you can get the same PWM signal on different GPIOs at the same time.

Before proceeding with this tutorial you should have the ESP32 add-on installed in your Arduino IDE. Follow one of the following tutorials to install the ESP32 on the Arduino IDE, if you haven’t already.

We also recommend taking a look at the following resources:

Watch the Video Tutorial

This tutorial is available in video format (watch below) and in written format (continue reading).

Parts Required

To follow this tutorial you need these parts:

You can use the preceding links or go directly to MakerAdvisor.com/tools to find all the parts for your projects at the best price!

ESP32 LED PWM Controller

The ESP32 has a LED PWM controller with 16 independent channels that can be configured to generate PWM signals with different properties.

Here’s the steps you’ll have to follow to dim an LED with PWM using the Arduino IDE:

1. First, you need to choose a PWM channel. There are 16 channels from 0 to 15.

2. Then, you need to set the PWM signal frequency. For an LED, a frequency of 5000 Hz is fine to use.

3. You also need to set the signal’s duty cycle resolution: you have resolutions from 1 to 16 bits. We’ll use 8-bit resolution, which means you can control the LED brightness using a value from 0 to 255.

4. Next, you need to specify to which GPIO or GPIOs the signal will appear upon. For that you’ll use the following function:

ledcAttachPin(GPIO, channel)

This function accepts two arguments. The first is the GPIO that will output the signal, and the second is the channel that will generate the signal.

5. Finally, to control the LED brightness using PWM, you use the following function:

ledcWrite(channel, dutycycle)

This function accepts as arguments the channel that is generating the PWM signal, and the duty cycle.

Dimming an LED

Let’s see a simple example to see how to use the ESP32 LED PWM controller using the Arduino IDE.

Schematic

Wire an LED to your ESP32 as in the following schematic diagram. The LED should be connected to GPIO 16.

(This schematic uses the ESP32 DEVKIT V1 module version with 30 GPIOs – if you’re using another model, please check the pinout for the board you’re using.)

Note: you can use any pin you want, as long as it can act as an output. All pins that can act as outputs can be used as PWM pins. For more information about the ESP32 GPIOs, read: ESP32 Pinout Reference: Which GPIO pins should you use?

Code

Open your Arduino IDE and copy the following code.

// the number of the LED pin
const int ledPin = 16;  // 16 corresponds to GPIO16

// setting PWM properties
const int freq = 5000;
const int ledChannel = 0;
const int resolution = 8;
 
void setup(){
  // configure LED PWM functionalitites
  ledcSetup(ledChannel, freq, resolution);
  
  // attach the channel to the GPIO to be controlled
  ledcAttachPin(ledPin, ledChannel);
}
 
void loop(){
  // increase the LED brightness
  for(int dutyCycle = 0; dutyCycle <= 255; dutyCycle++){   
    // changing the LED brightness with PWM
    ledcWrite(ledChannel, dutyCycle);
    delay(15);
  }

  // decrease the LED brightness
  for(int dutyCycle = 255; dutyCycle >= 0; dutyCycle--){
    // changing the LED brightness with PWM
    ledcWrite(ledChannel, dutyCycle);   
    delay(15);
  }
}

View raw code

You start by defining the pin the LED is attached to. In this case the LED is attached to GPIO 16.

const int ledPin = 16;  // 16 corresponds to GPIO16

Then, you set the PWM signal properties. You define a frequency of 5000 Hz, choose channel 0 to generate the signal, and set a resolution of 8 bits. You can choose other properties, different than these, to generate different PWM signals.

const int freq = 5000; 
const int ledChannel = 0; 
const int resolution = 8;

In the setup(), you need to configure LED PWM with the properties you’ve defined earlier by using the ledcSetup() function that accepts as arguments, the ledChannel, the frequency, and the resolution, as follows:

ledcSetup(ledChannel, freq, resolution);

Next, you need to choose the GPIO you’ll get the signal from. For that use the ledcAttachPin() function that accepts as arguments the GPIO where you want to get the signal, and the channel that is generating the signal. In this example, we’ll get the signal in the ledPin GPIO, that corresponds to GPIO 16. The channel that generates the signal is the ledChannel, that corresponds to channel 0.

ledcAttachPin(ledPin, ledChannel);

In the loop, you’ll vary the duty cycle between 0 and 255 to increase the LED brightness.

for(int dutyCycle = 0; dutyCycle <= 255; dutyCycle++){
    // changing the LED brightness with PWM
    ledcWrite(ledChannel, dutyCycle);
    delay(15); 
}

And then, between 255 and 0 to decrease the brightness.

for(int dutyCycle = 255; dutyCycle >= 0; dutyCycle--){
    // changing the LED brightness with PWM
    ledcWrite(ledChannel, dutyCycle);
    delay(15);
 }

To set the brightness of the LED, you just need to use the ledcWrite() function that accepts as arguments the channel that is generating the signal, and the duty cycle.

ledcWrite(ledChannel, dutyCycle);

As we’re using 8-bit resolution, the duty cycle will be controlled using a value from 0 to 255. Note that in the ledcWrite() function we use the channel that is generating the signal, and not the GPIO.

Testing the Example

Upload the code to your ESP32. Make sure you have the right board and COM port selected. Look at your circuit. You should have a dimmer LED that increases and decreases brightness.

Getting the Same Signal on Different GPIOs

You can get the same signal from the same channel in different GPIOs. To achieve that, you just need to attach those GPIOs to the same channel on the setup().

Let’s modify the previous example to dim 3 LEDs using the same PWM signal from the same channel.

Schematic

Add two more LEDs to your circuit by following the next schematic diagram:

(This schematic uses the ESP32 DEVKIT V1 module version with 30 GPIOs – if you’re using another model, please check the pinout for the board you’re using.)

Code

Copy the following code to your Arduino IDE.

// the number of the LED pin
const int ledPin = 16;  // 16 corresponds to GPIO16
const int ledPin2 = 17; // 17 corresponds to GPIO17
const int ledPin3 = 5;  // 5 corresponds to GPIO5

// setting PWM properties
const int freq = 5000;
const int ledChannel = 0;
const int resolution = 8;
 
void setup(){
  // configure LED PWM functionalitites
  ledcSetup(ledChannel, freq, resolution);
  
  // attach the channel to the GPIO to be controlled
  ledcAttachPin(ledPin, ledChannel);
  ledcAttachPin(ledPin2, ledChannel);
  ledcAttachPin(ledPin3, ledChannel);
}
 
void loop(){
  // increase the LED brightness
  for(int dutyCycle = 0; dutyCycle <= 255; dutyCycle++){   
    // changing the LED brightness with PWM
    ledcWrite(ledChannel, dutyCycle);
    delay(15);
  }

  // decrease the LED brightness
  for(int dutyCycle = 255; dutyCycle >= 0; dutyCycle--){
    // changing the LED brightness with PWM
    ledcWrite(ledChannel, dutyCycle);   
    delay(15);
  }
}

View raw code

This is the same code as the previous one but with some modifications. We’ve defined two more variables for two new LEDs, that refer to GPIO 17 and GPIO 5.

const int ledPin2 = 17; // 17 corresponds to GPIO17 
const int ledPin3 = 5;  // 5 corresponds to GPIO5

Then, in the setup(), we’ve added the following lines to assign both GPIOs to channel 0. This means that we’ll get the same signal, that is being generated on channel 0, on both GPIOs.

ledcAttachPin(ledPin2, ledChannel); 
ledcAttachPin(ledPin3, ledChannel);

Testing the Project

Upload the new sketch to your ESP32. Make sure you have the right board and COM port selected. Now, take a look at your circuit:

All GPIOs are outputting the same PWM signal. So, all three LEDs increase and decrease the brightness simultaneously, resulting in a synchronized effect.

Wrapping Up

In summary, in this post you’ve learned how to use the LED PWM controller of the ESP32 with the Arduino IDE to dim an LED. The concepts learned can be used to control other outputs with PWM by setting the right properties to the signal.

We have other tutorials related with ESP32 that you may also like:

This is an excerpt from our course: Learn ESP32 with Arduino IDE. If you like ESP32 and you want to learn more, we recommend enrolling in Learn ESP32 with Arduino IDE course.

[eBook] Build Web Servers with ESP32 and ESP8266 (2nd Edition)

Build Web Server projects with the ESP32 and ESP8266 boards to control outputs and monitor sensors remotely. Learn HTML, CSS, JavaScript and client-server communication protocols DOWNLOAD »

Recommended Resources

Build a Home Automation System from Scratch » With Raspberry Pi, ESP8266, Arduino, and Node-RED.

Home Automation using ESP8266 eBook and video course » Build IoT and home automation projects.

Arduino Step-by-Step Projects » Build 25 Arduino projects with our course, even with no prior experience!

What to Read Next…

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32 thoughts on “ESP32 PWM with Arduino IDE (Analog Output)”

Abdelouahed

October 30, 2018 at 5:45 pm

Hi,

This is a good tutorial for PWM or analog output, however could you try my analogWrite implementation for ESP?

Please give it a shout here https://github.com/ERROPiX/ESP32_AnalogWrite

Thank you
Reply
- Sara Santos
  
  November 1, 2018 at 11:27 am
  
  Hi.
  Thank you for sharing that library.
  I’ll give it a try, and update the article to include your solution.
  Regards,
  Sara 🙂
  Reply
dale wolver

October 31, 2018 at 1:23 pm

Trying to figure out where the ledxxxxx functions are defined. Don’t see any #include x.h in the codes
Reply
- Sara Santos
  
  November 1, 2018 at 11:24 am
  
  Hi dale.
  Those functions are part of the ESP32 core library for the Arduino IDE by default.
  So, once you have ESP32 installed on Arduino IDE, you don’t need to include anything else in your code to use those functions.
  Regards,
  Sara 🙂
  Reply
Ravija

October 31, 2018 at 3:29 pm

Good & simple
Reply
- Sara Santos
  
  November 1, 2018 at 11:23 am
  
  Thanks 🙂
  Reply
Łukasz Heczko

December 28, 2018 at 9:18 pm

Hi, I’m trying to connect LED PWM and servo. PWM works perfect, but when I write
myservo.attach(33); to setup PWM stops working. Using
https://randomnerdtutorials.com/esp32-servo-motor-web-server-arduino-ide/

Any idea?
Reply
- Sara Santos
  
  December 31, 2018 at 2:18 pm
  
  Hi Lucasz.
  Can you provide more details?
  Are you getting any error on the serial monitor?
  Regards,
  Sara
  Reply
Vitaly

March 31, 2019 at 11:04 am

Hi Sara,
“All GPIOs are outputting the same PWM signal. So, all three LEDs increase and decrease the brightness simultaneously, resulting in a synchronized effect.”

Is itpossible to setup the different channels with different frequency and PWM in order to control the LED brightness separately?
Reply
- Sara Santos
  
  March 31, 2019 at 3:47 pm
  
  Hi.
  Yes, you can do that.
  However, please note that 0 and 1 will share the same frequency, as well as channels 2 and 3, 5 and 5. See this discussion that might be helpful: https://rntlab.com/question/esp32-pwm-frequency-selection/
  Regards,
  Sara
  Reply
Ben Warem

March 5, 2020 at 11:25 am

You can also use macros when defining constants.
So instead of const int ledPin = 16, you can use:
#define LEDPIN 16
it saves memory
Reply
Stéphane

March 10, 2020 at 4:32 pm

const int ledPin = 16

Will not actually consume any RAM: the compiler knows there is no reason to create a variable in RAM, so it’ll stay out of RAM (it will be stored in flash memory).

#define ledPin 16

Can actually become a bad practice… Why?
Because it can lead to very hard to find bugs.
Think about this mistake:

#define ledPin 16;

The “text-replace” nature of #define can mislead you with a stray semicolon or other unexpected replace…

Apart from that, concerning the desired light effect on a LED, here is a simple idea to give the impression that it breathes:

void loop(){
ledcWrite(ledChannel, 128 – 128 * cos(2*PI*(millis() % 2001)/2000));
}
Reply
omali

April 3, 2020 at 9:45 am

hi
can I have different frequencies for each of 16 pins?
(different PWMs with adjaustble duty cycles and frequencies for all pins)?
Reply
- Sara Santos
  
  April 3, 2020 at 10:23 am
  
  Hi.
  In theory, that’s possible. You need to create different PWM channels with different frequencies.
  However, I’m not sure if in practical terms, the ESP32 can handle all the 16 channels at the same time. You have to experiment to find out.
  Regards,
  Sara
  Reply
  - omali
    
    April 4, 2020 at 11:42 am
    
    thank you very much for the reply.
    one another question
    can we change the frequency of a channel while running the program (with coding in the loop)?
    without resetting the esp?
    Reply
    - Sara Santos
      
      April 4, 2020 at 3:02 pm
      
      Hi. I never tried that.
      But, it should be possible.
      Regards,
      Sara
      Reply
    - Mike
      
      July 20, 2020 at 1:50 pm
      
      I have tried this driving a two tone sounder.
      
      change the frequency with ledcSetup(), and remember to then perform a ledcWrite().
      
      void loop() {
      // put your main code here, to run repeatedly:
      ledcSetup(1, 2048, 8);
      ledcWrite(1, 127);
      delay(2000);
      ledcSetup(1, 4069, 8);
      ledcWrite(1, 127);
      delay(2000);
      }
      Reply
Mark Grass

June 1, 2020 at 1:10 am

I’ve used Arduinos for a long time now but now need to use the ESP32 Devkit. I need to drive 4 motors (same freq for each, but different duty cycle) and I need to drive two or four RC type servos. When I run code for PWM for the BLDC motors, it works fine. If I run code to just position the servos, it works fine. When I try to combine the code, it appears that setting the freq for the PWM messes up the servos. It doesn’t want to give me a 50Hz frame rate. Do you know if there is a conflict between the servo library and the standard PWM functions of the ESP32? I’ve bought two of your courses, but the answer doesn’t seem to be there and I haven’t found anything online yet.
Reply
- Sara Santos
  
  June 1, 2020 at 2:26 pm
  
  Hi Mark.
  Please post your question on the RNTLAB forum. I can help you better there: https://rntlab.com/forum/
  Just login with the email you used to buy the courses.
  Regards,
  Sara
  Reply
Donald Garber

September 28, 2020 at 11:43 pm

I’m wondering and confounded by how you would set off a second (or more) LED light at a different time, but repeat the same cycle as the first LED? Say, when the first LED begins to decrease brightness, the second LED would start to increase its brightness.

I’ve tried calling a custom function nextLight() within the for loop. Doing that simply stops the first LED’s cycle while the nextLight LED runs fully. It’s wonky. Unintuitive.

const int redLED1=26;
const int redLED2=25;

// setting PWM properties
const int freq=5000; // 5000Hz for our LEDs here
const int freq2=5000;
const int ledChannel=0;
const int ledChannel2=2;
const int resolution=8;
const int resolution2=8;

void setup() {
ledcSetup(ledChannel, freq, resolution);
ledcSetup(ledChannel2,freq2,resolution2);
// attach the channel to the GPIO to be controlled
ledcAttachPin(redLED1, ledChannel);
ledcAttachPin(redLED2, ledChannel2);

Serial.begin(115200);

}

void loop() {
// put your main code here, to run repeatedly:

//increase LED brightness channel 1
for(int dutyCycle=0;dutyCycle<=255; dutyCycle++){
// changing the LED brightness with PWM
ledcWrite(ledChannel, dutyCycle);
delay(15);
}
// decrease LED brightness channel 1
for(int dutyCycle=255;dutyCycle>=0;dutyCycle–){
// changing the LED brightness with PWM
if(dutyCycle==250){
nextLight():
}
ledcWrite(ledChannel, dutyCycle);
delay(15);
}
}

void nextLight(){
for(int dutyCycle=0;dutyCycle<=255; dutyCycle++){
// changing the LED brightness with PWM
ledcWrite(ledChannel2, dutyCycle);
delay(15);
}
for(int dutyCycle=255;dutyCycle>=0;dutyCycle–){
// changing the LED brightness with PWM
ledcWrite(ledChannel2, dutyCycle);
delay(15);
}
}
Reply
- Sara Santos
  
  September 29, 2020 at 11:16 am
  
  Hi.
  Have you considered using tasks?
  Read this tutorial: https://randomnerdtutorials.com/esp32-dual-core-arduino-ide/
  Regards,
  Sara
  Reply
- Feng
  
  February 2, 2021 at 10:15 pm
  
  Did you try this?
  ledcWrite(ledChannel1, 255-dutyCycle);
  Reply
Donald Garber

September 29, 2020 at 4:38 pm

Thank you Sara.
Reply
Mel Lieberman

November 22, 2020 at 12:18 pm

I tried the PWM example as coded in the tutorial and it did not function. I looked at a PinOut of a 30 Pin ESP32 board and found that ADC channel 0 is on the same pin as GP04. I moved the led to GP04, changed the code to reflect the move and the PWM example is now functional. It seems as if ADC channels are tied to specific GPIO’s.
Reply
Long Nhan

February 5, 2021 at 4:19 pm

Hi! I haven’t understood the channel that we need to choose. what is it depend on? in your code I have tried to change the channel from 0 to 2 It still worked.
Reply
- Sara Santos
  
  February 6, 2021 at 11:44 am
  
  Hi.
  You can choose any channel from 0 to 15.
  Regards,
  Sara
  Reply
byron sag

February 10, 2021 at 5:26 am

Hello Sara, I am writing to you from Ecuador, my question is how can I perform a power control of a led using a potentiometer in an MCU Esp 32, thank you very much
Reply
Forrest Erickson

April 10, 2021 at 9:23 pm

Hello Sarah,
I am not sure I understand the nature of the programmability of the LED channels and
I feel confused by this sentence above, “You can get the same signal from the same channel in different GPIOs.”

Might it be,
You can set the same PWM signal to more than one GPIOs.
Is it that you set a GPIO to a channel?
Or are we setting a channel more than once to different GPIOs.

For what it is worth I am on page 304 of your Building Web Server book and am getting a lot of value out of the book! I came here to better understand the LED and PWM system in the ESP32.

Thanks,
Forrest Erickson
Reply
- Sara Santos
  
  April 12, 2021 at 9:27 am
  
  Hi Forrest.
  
  What I mean by “You can get the same PWM signal on more than one GPIO” is that you can set the same PWM signal (and the same channel) on more than one GPIO.
  
  In the ESP32, PWM channels produce PWM signals. You then attach those channels to the GPIOs where you want to have the signals. If you want to have the same signals on multiple GPIOs, you don’t need to create multiple PWM channels. You can use the same channel for multiple GPIOs.
  
  For example, it is possible to have the following scenarios:
  – PWM channel 1 –> signal on GPIO 23
  – PWM channel 1 –> signal on GPIO 22
  – PWM channel 1 –> signal on GPIO 21
  All GPIOs will have the same PWM signal.
  
  I’m sorry if this is confusing. English is not my native language, and sometimes my sentences seem clear to me, but not so much for others.
  
  Regards,
  Sara
  Reply
  - Forrest Erickson
    
    April 12, 2021 at 3:55 pm
    
    Sara,
    
    Thanks for the clarification. You did great. Re: “English is not my native language, and sometimes my sentences seem clear to me, but not so much for others.”
    It is my native and I still mangle it.
    
    I still had questions about the independence of the setup of the channels and did some experimenting based on your example code. I have pushed the results of the experiments to my github at: https://github.com/ForrestErickson/PWMExperiments
    
    Bottom line. You cannot program the frequency of channel 0 and 1. The last one you set governs both.
    I also experimented with higher frequencies and resolutions and here is a summary of what I found:
    // Set Freq: 80KHz 100KHz 200KHz 50KHz
    //const int resolution = 8; // Freq became 80.00 100.00 200.00
    //const int resolution = 9; // Freq became 80.00 100.0 156.3
    const int resolution = 10; // Freq became 78.13 78.13 78.13 50.00
    //const int resolution = 11; // Freq became 39.06 39.06 39.06
    //const int resolution = 12; // Freq became 19.53 19.53 19.53
    
    Hope this helps visitors.
    Reply
    - Forrest Erickson
      
      April 12, 2021 at 3:57 pm
      
      Should have said, “Bottom line. You cannot INDEPENDENTLY program the frequency of channel 0 and 1.”
      Reply
      - Sara Santos
        
        April 12, 2021 at 9:49 pm
        
        Thanks for sharing your results.
        It will definitely be useful for our readers.
        Regards,
        Sara

ESP32 PWM with Arduino IDE (Analog Output)

Watch the Video Tutorial

Parts Required

ESP32 LED PWM Controller

Dimming an LED

Schematic

Code

Testing the Example

Getting the Same Signal on Different GPIOs

Schematic

Code

Testing the Project

Wrapping Up

[eBook] Build Web Servers with ESP32 and ESP8266 (2nd Edition)

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