YAGNI

The ESP32 is a family of cost accessible microcontrollers with many features that make them attractive to embedded systems hobbyists.

ESP-IDF is Esspressif's official IoT development framework for a number of ESP32 SoC. Gentoo's main repository doesn't provide an ebuild for this framework, but it's available in the GURU repository.

This post will explain the steps to install the ESP-IDF framework, then use it to build a sample project and flash it into a ESP32-C3 development board.

Enable the GURU repository and synchronize it, the preferred way is using eselect-repository:

eselect repository enable guru
emaint sync -r guru

It's important to enable the riscv32 use flag if one is going to be developing for a board with a RISCV microcontroller (i.e. ESP32-C3).

By the time of this writing, the following packages had to be unmasked before being able to install the framework:

$ cat /etc/portage/package.accept_keywords/esp-idf 
dev-embedded/esp-*::guru
dev-embedded/freertos-gdb::guru
dev-embedded/idf-component-manager::guru
dev-python/jsonref
dev-python/kconfiglib
dev-python/pydantic-settings
dev-python/schema

Install the ESP-IDF framework:

emerge -a esp-idf

The ESP-IDF framework comes with a number of examples. This section explains the steps to follow for building and flashing the hello_world project included in the framework:

$ equery f esp-idf | grep get-started/hello_world
/usr/share/esp-idf/examples/get-started/hello_world
/usr/share/esp-idf/examples/get-started/hello_world/CMakeLists.txt
/usr/share/esp-idf/examples/get-started/hello_world/README.md
/usr/share/esp-idf/examples/get-started/hello_world/main
/usr/share/esp-idf/examples/get-started/hello_world/main/CMakeLists.txt
/usr/share/esp-idf/examples/get-started/hello_world/main/hello_world_main.c
/usr/share/esp-idf/examples/get-started/hello_world/pytest_hello_world.py
/usr/share/esp-idf/examples/get-started/hello_world/sdkconfig.ci

To build the project, copy the hello_world direcotyr to a place with write permissions (i.e. the user's home direcory).

cp -r /usr/share/esp-idf/examples/get-started/hello_world ~
cd ~/hello_world

Now configure the project's target to the correct development board; in this example it's set to esp32c3 that corresponds to the ESP32-C3-DevKitC.

idf set-target esp32c3

Connect the development board to the computer and proceed to build it, flash it and monitor the execution:

idf build
idf flash monitor

The PORT used for flashing the microcontroller should be automatically detected; if it wasn't, refer to the links in the See also section.

1. The ESP-IDF repository
2. The ESP-IDF programming guide
3. Build the hello_world example from the manual