Documentation Contribution Guidelines


This is a guideline for the Arduino ESP32 project documentation. The idea for this guideline is to show how to start collaborating on the project.

The guideline works to give you the directions and to keep the documentation more concise, helping users to better understand the structure.

About Documentation

We all know how important documentation is. This project is no different.

This documentation was created in a collaborative and open way, letting everyone contribute, from a small typo fix to a new chapter writing. We try to motivate our community by giving all the support needed through this guide.

The documentation is in English only. Future translations can be added when we finish the essential content in English first.

How to Collaborate

Everyone with some knowledge to share is welcome to collaborate.

One thing you need to consider is the fact that your contribution must be concise and assertive since it will be used by people developing projects. The information is very important for everyone, be sure you are not making the developer’s life harder!

Documentation Guide

This documentation is based on the Sphinx with reStructuredText and hosted by ReadTheDocs.

If you want to get started with Sphinx, see the official documentation:

First Steps

Before starting your collaboration, you need to get the documentation source code from the Arduino-ESP32 project.

  • Step 1 - Fork the Arduino-ESP32 to your GitHub account.

  • Step 2 - Check out the recently created fork.

  • Step 3 - Create a new branch for the changes/addition to the docs.

  • Step 4 - Write!


To properly work with the documentation, you need to install some packages in your system.

pip install -U Sphinx
pip install -r requirements.txt

The requirements file is under the docs folder.

Using Visual Studio Code

If you are using the Visual Studio Code, you can install some extensions to help you while writing documentation.

reStructuredText Pack

We also recommend you install to grammar check extension to help you to review English grammar.



To build the documentation and generate the HTLM files, you can use the following command inside the docs folder. After a successful build, you can check the files inside the build/html folder.

make html

This step is essential to ensure that there are no syntax errors and also to see the final result.

If everything is ok, you will see some output logs similar to this one:

Running Sphinx v2.3.1
loading pickled environment... done
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 35 source files that are out of date
updating environment: [extensions changed ('sphinx_tabs.tabs')] 41 added, 3 changed, 0 removed
reading sources... [100%] tutorials/tutorials
looking for now-outdated files... none found
pickling environment... done
checking consistency... done
preparing documents... done
writing output... [100%] tutorials/tutorials
generating indices...  genindexdone
writing additional pages...  searchdone
copying images... [100%] tutorials/../_static/tutorials/peripherals/tutorial_peripheral_diagram.png
copying static files... ... done
copying extra files... done
dumping search index in English (code: en)... done
dumping object inventory... done
build succeeded.

The HTML pages are in build/html.


The Arduino ESP32 is structured in some sections to make it easier to maintain. Here is a brief description of this structure.


In this section, you will include all the documentation about drivers, libraries, and any other related to the core.

In this section, we do not add general information. For more general information, we have sections for other related parts, like the FAQ, library builder, troubleshooting, etc.


Here is the place to add any special guide on the development boards, pin layout, schematics, and any other relevant content.


In this folder, you can add all common information used in several different places. This helps to make documentation easily maintainable.


This is the place to add the guides for common applications, IDEs configuration, and any other information that can be used as a guideline.


If you want to add a specific tutorial related to the Arduino core for ESP32, this is the place. The intention is not to create a blog or a demo area, but this can be used to add some complex description or to add some more information about APIs.

Images and Assets

All the files used on the documentation must be stored in the _static folder. Be sure that the content used is not with any copyright restriction.

Documentation Rules

Here are some guidelines to help you. We also recommend copying a sample file from the same category you are creating.

This will help you to follow the structure as well as to get inspired.

Basic Structure

To help you create a new section from scratch, we recommend you include this structure in your content if it applies.

  • About - Brief description of the document.
    • Description of the peripheral, driver, protocol, including all different modes and configurations.

  • API - Description of each public function, macros, and structs.

  • Basic Usage

  • Example Application

About Section

In this section, you need to add a brief description of the API. If you are describing a peripheral API, you should explain a little bit about the peripheral and the working modes, if it’s applicable.

API Functions

To add a new function description, you must know that the users only have access to the public functions.

Here is an example of how to add the function description from I2C API:


This function is used to define the ``SDA`` and ``SCL`` pins.

.. note:: Call this function before ``begin`` to change the pins from the default ones.

.. code-block:: arduino

    bool setPins(int sdaPin, int sclPin);

* ``sdaPin`` sets the GPIO to be used as the I2C peripheral data line.

* ``sclPin`` sets the GPIO to be used as the I2C peripheral clock line.

The default pins may vary from board to board. On the *Generic ESP32* the default I2C pins are:

* ``sdaPin`` **GPIO21**

* ``sclPin`` **GPIO22**

This function will return ``true`` if the peripheral was configured correctly.

Be sure to include a very comprehensive description, add all the parameters in and out, and describe the desired output.

If the function uses a specific structure, you can also describe the structure in the same function block or add a specific section if the structure is shared with other functions.

Basic Usage

Some APIs are more complex to use or require more steps in order to configure or initialize. If the API is not straightforward in terms of usability, please consider adding a how-to-use section describing all the steps to get the API configured.

Here is an example:

Basic Usage

To start using I2C as slave mode on the Arduino, the first step is to include the ``Wire.h`` header to the sketch.

.. code-block:: arduino

    #include "Wire.h"

Before calling ``begin``, you must create two callback functions to handle the communication with the master device.

.. code-block:: arduino



.. code-block:: arduino


The ``onReceive`` will handle the request from the ``master`` device upon a slave read request and the ``onRequest`` will handle the answer to the master.

Now, we can start the peripheral configuration by calling ``begin`` function with the device address.

.. code-block:: arduino


By using ``begin`` without any arguments, all the settings will be done by using the default values. To set the values on your own, see the function description. This function is described here: `i2c begin`_

Example Application

It is very important to include at least one application example or a code snippet to help people using the API.

If the API does not have any application example, you can embed the code directly. However, if the example is available, you must include it as a literal block.

.. literalinclude:: ../../../libraries/WiFi/examples/WiFiAccessPoint/WiFiAccessPoint.ino
    :language: arduino

Sphinx Basics

Heading Levels

The heading levels used on this documentation are:

  • H1: - (Dash)

  • H2: * (Asterisk)

  • H3: ^ (Circumflex)

  • H4: # (Sharp)

Code Block

To add a code block, you can use the following structure:

.. code-block:: arduino
    bool begin(); //Code example


To include images in the docs, first, add all the files into the _static folder with a filename that makes sense for the topic.

After that, you can use the following structure to include the image in the docs.

.. figure:: ../_static/arduino_i2c_master.png
    :align: center
    :width: 720
    :figclass: align-center

You can adjust the width according to the image size.

Be sure the file size does not exceed 600kB.


If you need support on the documentation, you can ask a question in the discussion here.

Additional Guidelines

If you want to contribute with code on the Arduino ESP32 core, be sure to follow the ESP-IDF Documenting Code as a reference.