This project is a PID controller for a Gaggia Paros (or Gaggia Classic) coffee machine using Arduino and a few other components. This Arduino based controller improves the stability of the water temperature of the coffee machine by controlling the boiler with a PID control loop feedback.

This project is based on lib_coffee_machine which is a C++ library providing an abstraction of a generic coffee machine.

This project implements the library interfaces targeting an Arduino Nano platform and several sensors and displays.

This project depends on the following Arduino libraries:

• PID
• TSIC
• SDD1306Ascii
• MAX6675

The Makefile at the project root directory provides targets to build the code and the documentation.

You can build the code with different approaches:

• with the Arduino IDE opening the CoffeeMachine.ino sketch
• with VSCode and the Arduino extension opening the CoffeeMachine.ino sketch
• with make build using Docker

The code can be built inside a Docker container using docker-compose. The docker-compose.yml and the Dockerfile are in the docker directory. The docker-compose.yml depends on 2 environment variables that must be defined before starting the build:

• CORE: the Arduino core
• BOARD: the Arduino board to use

Refer to the arduino-cli documentation for the list of available cores and boards. The following is an example that builds the code for an Arduino Nano board:

$ cd /path/to/repo
$ CORE=avr BOARD=nano make build

The generated build files will be in the CoffeeMachine/build directory.

After building the Docker image the first time, you can then use the arduino-cli installed in the Docker image directly with:

$ cd /path/to/repo
$ docker run --rm -it -v $PWD:/build arduino-builder arduino-cli version
arduino-cli Version: 0.10.0 Commit: ec5c3ed

This is the list of components I used for the project:

• 1x Arduino Nano (any board type will do)
• 1x Solid State Relay 40A
• 2x Digital temperature sensors (e.g. TSic306)
• 1x I2C 128x64 OLED
• Wires and other supplies

Read the project documentation at: https://arduinocoffeemachine.readthedocs.io

Or build it locally with:

$ cd /path/to/repo
$ make docs

The tools directory contains a Python script that can be used to read the Arduino Serial messages and to plot the current water temperature on a graph. The goal is to help the PID tuning process showing the realtime results.

$ cd tools
$ poetry install --no-dev
$ poetry run python temp_plotter.py

A big thanks goes to these two other projects that helped me a lot in the understanding of the electric schematics of the coffee machine and the components to use:

• RaspberryPI based
• Arduino based