Cofcon is a simple PID-based controller for espresso and coffee machines. It only needs an Arduino-Compatible microcontroller, a temperature-sensor and a SSR to control the heating of the espresso machine. This is not another copy-and-paste-PID, instead the Arduino-PID-Library by br3ttb are used as these controller seems to work very stable with standard-parameters and allows auto-tuning to achieve a very high temperature stability (about 0.1°C in the case of my Gaggia CC). The basic idea of the heater control and parts of the code are based on BBCC by Tim Hirzel which can be found on Arduino Playground, the serial interface code and graphing output should be compatible. The code is designed in a (more or less) modular way so new modules or even a simple simulation for testing purposes can be selected using preprocessor defines in the main file. It is possible to control the board vie bluetooth using a HC-xx-modue for your Arduino. A simple control-app has been designed using the MIT AppInventor2, but it is still in development stage. For details on the app see the README-File in the android-directory.
- an espresso machine where you have access to the heating power connection/thermostat switch (obviously). One warning: You should have the schematics/powering scheme and you should know what you are doing ! Please be careful, always UNPLUG the machine before you open it (yes, really UNPLUG - it needs to be disconnected from the AC line).
- an arduino-compatible microcontroller - tests have been performed with the UNO and NANO but in principle any other controller should do. You only need 3-4 IO-Pins, so even a simple ATTINY-board should be enough.
- one (or more) temperature-sensors - this controller has been running with the digital Dallas DS18B20 and TSIC-306 so far, but feel free to implement any other sensor type and contribute to this project
- a SSR which is capable of switching your load due to the heating. Usually a SSR capable of switching 8-10A at 240V should be fine, but be sure to check the power consumption of you machine before
- a few cables, maybe pull-up/protection resistors depending on the sensors and SSR you are using
- Arduino-PID-Library installed in your arduino/libraries
- custom libraries depending on the sensors you are using (wire, dallas, tsic) which are available here on github or Arduino Playground
- have the libraries needed for this project installed in your arduino/libraries
- cope the cofcon-folder with its sketch files into your arduino-folder
- restart your Arduino-IDE and the project 'cofcon' should show up in your Sketchbook-Menu
- (de)activate the sensors you want to use with the #define-switches of cofcon.ino
- by default, a simple simulation-mode is activated for testing purposes (deactivate by commenting out the #define SIMULATION_MODE)