ESP32 Arduino CLI

This is a sample project on how to use the Arduino CLI to compile and upload code to an ESP32 board. It uses the Just task runner to provide a convenient way to run the commands, which isn’t strictly necessary, but makes it convenient and less error-prone than a Makefile.

Also you can change variables on the fly with CLI flags and such, which is quite nice.

Prerequisites

• Arduino CLI
• Just

Usage

You don’t need to clone this repo, I suggest you instead copy the justfile and adjust it to your needs. You do however need to install the ESP32 core. You can do that through the Arduino CLI or use the GUI if you have the Arduino IDE installed.

$ arduino-cli core update-index
$ arduino-cli core install esp32:esp32

Then create a folder for your project with your sketch and the justfile. It’s important that the name of the folder is the same as the name of the sketch, so that the Arduino CLI can find it. In the case of this example, the folder is called esp32-arduino-cli and the sketch is called esp32-arduino-cli.ino.

Then you can run the commands:

# compile, upload, and connect the serial monitor
$ just

# or run the them individually
$ just build
$ just upload
$ just monitor
$ just info

Depending on your shell, Just should also automatically provide tab completions for commands as well as variables you can change per run.

Configuration

Board (FQBN)

Depending on your ESP32 board you may need to adjust the board variable in the justfile. I am using the S3 variant, but the "default" (if there is such a thing with all the different ESP32 variants) is most likely the esp32:esp32:esp32 variant. I have one of those too and that’s what works.

Upload- and Serial Speeds

If you get an error uploading your sketch, try decreasing the upload_speed to 460800 (half the default). The serial monitor speed is most likely fine, but you can also reduce it (just make sure it matches the value in your sketch when you initialize it). Run just info for other possible values.

Board Port

Depending on your OS the command to find the port may differ. I suggest you connect your board and run ls -l /dev | grep usb and see what shows up, then adjust the port command accordingly.

Other Options & Default Values

You can run the following command to see all available build options for your board, their default values as well as some info about your board. Generally these options are used during the build step and you can add them to your justfile.

$ just info

License

Unlicense.

Really just do whatever you want with this, it’s just a helpful collection of commands. If you make improvements and feel like sharing them, you’re welcome to do so through a pull request.

🖖