Using Espressif IoT Development Framework with the ESP32

Setting Up ESP-IDF

In the docs directory you will find per-platform setup guides:

• Windows Setup Guide
• Mac OS Setup Guide
• Linux Setup Guide

Finding A Project

As well as the esp-idf-template project mentioned in the setup guide, esp-idf comes with some example projects in the examples directory.

Once you've found the project you want to work with, change to its directory and you can configure and build it:

Configuring your project

make menuconfig

Compiling your project

make all

... will compile app, bootloader and generate a partition table based on the config.

Flashing your project

When make all finishes, it will print a command line to use esptool.py to flash the chip. However you can also do this from make by running:

make flash

This will flash the entire project (app, bootloader and partition table) to a new chip. The settings for serial port flashing can be configured with make menuconfig.

You don't need to run make all before running make flash, make flash will automatically rebuild anything which needs it.

Viewing Serial Output

The make monitor target will use the already-installed miniterm (a part of pyserial) to display serial output from the ESP32 on the terminal console.

Exit miniterm by typing Ctrl-].

To flash and monitor output in one pass, you can run:

make flash monitor

Compiling & Flashing Just the App

After the initial flash, you may just want to build and flash just your app, not the bootloader and partition table:

• make app - build just the app.
• make app-flash - flash just the app.

make app-flash will automatically rebuild the app if it needs it.

(There's no downside to reflashing the bootloader and partition table each time, if they haven't changed.)

Parallel Builds

esp-idf supports compiling multiple files in parallel, so all of the above commands can be run as make -jN where N is the number of parallel make processes to run (generally N should be equal to or one more than the number of CPU cores in your system.)

Multiple make functions can be combined into one. For example: to build the app & bootloader using 5 jobs in parallel, then flash everything, and then display serial output from the ESP32 run:

make -j5 flash monitor

The Partition Table

Once you've compiled your project, the "build" directory will contain a binary file with a name like "my_app.bin". This is an ESP32 image binary that can be loaded by the bootloader.

A single ESP32's flash can contain multiple apps, as well as many different kinds of data (calibration data, filesystems, parameter storage, etc). For this reason a partition table is flashed to offset 0x4000 in the flash.

Each entry in the partition table has a name (label), type (app, data, or something else), subtype and the offset in flash where the partition is loaded.

The simplest way to use the partition table is to make menuconfig and choose one of the simple predefined partition tables:

• "Single factory app, no OTA"
• "Factory app, two OTA definitions"

In both cases the factory app is flashed at offset 0x10000. If you make partition_table then it will print a summary of the partition table.

For more details about partition tables and how to create custom variations, view the docs/partition-tables.rst file.

Erasing Flash

The make flash target does not erase the entire flash contents. However it is sometimes useful to set the device back to a totally erased state, particularly when making partition table changes or OTA app updates. To erase the entire flash, run make erase_flash.

This can be combined with other targets, ie make erase_flash flash will erase everything and then re-flash the new app, bootloader and partition table.

Resources

• The docs directory of the esp-idf repository contains source of esp-idf documentation.

• The esp32.com forum is a place to ask questions and find community resources.

• Check the Issues section on github if you find a bug or have a feature request. Please check existing Issues before opening a new one.

• If you're interested in contributing to esp-idf, please check the Contributions Guide.