I am using a Windows desktop and I run Linux as a Virtualbox guest. ESP32 development under Windows is super easy to set up – you only need to install the Arduino IDE. Unfortunately, it really bugged me that compilation time is so slow. I’m not enough experienced and test a lot on the real hardware, and slow compilation really slows down the entire development process.

The Arduino IDE v2 has improved and supports parallel compilation within a submodule, but still it works slower than expected on my computer and is not ideally parallelized. Additionally, I noticed that some libraries are recompiled every time which is a huge waste of time (and resources) because libraries don’t change. Only my sketch source code changes.

I decided to see how compilation performs on Linux. The Arduino project has a command-line tool to manage, compile and upload code. The tool is still in active development but works flawlessly for me.

Here is how I installed it on my Linux desktop:

wget https://downloads.arduino.cc/arduino-cli/arduino-cli_latest_Linux_64bit.tar.gz
tar -xf arduino-cli_latest_Linux_64bit.tar.gz
mv arduino-cli ~/bin/
rm arduino-cli_latest_Linux_64bit.tar.gz

arduino-cli config init
vi /home/famzah/.arduino15/arduino-cli.yaml
  # board_manager -> additional_urls -> add "https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json"
  # library -> enable_unsafe_install -> set to "true" # so that we can install .zip libraries
arduino-cli core update-index
arduino-cli core install esp32:esp32
arduino-cli board listall # you must see lots of "esp32" boards now

Here is how to compile a sketch and upload it to an ESP32 board:

cd %the_folder_where_you_saved_your_Arduino_sketch%

arduino-cli compile --warnings all -b esp32:esp32:nodemcu-32s WifiRelay.ino --output-dir /tmp/this-sketch-tmp

arduino-cli upload -v --input-dir /tmp/this-sketch-tmp -p /dev/ttyUSB0 -b esp32:esp32:nodemcu-32s

arduino-cli monitor -p /dev/ttyUSB0 -c baudrate=115200

I have created a small script to automate this task which also uses a dynamically created temporary folder, in order to avoid race conditions and artefacts. The sketch folder on my Windows host is shared (read-only) with my Linux guest. I still write the sketch source code on my Windows machine using the Arduino IDE.

The ESP32 board is connected to my Windows host but I need to communicate with it from my Linux guest. This is done easily in Virtualbox using USB filters. A USB filter allows you to do a direct pass-through of the ESP32 serial port. It also works if you plug in the ESP32 board dynamically while the Linux machine is already running.