SmartCoil

Full interface to automate a home-based fan coil unit with a Raspberry Pi.

DISCLAIMER: Notice that fan coil unit wiring may involve high voltage manipulation, any handling of this kind is under your own responsibility.

Pictures of the GUI and home-made case views are listed below.

This project is based in the following technologies:

• Kivy for GUI that allows temperature and fan speed manipulation through a PiTFT touch screen.
• BME680 sensor for current temperature, humidity and air quality information in the GUI.
• 4-channel relay module to control coil valve and fan states.
• Meteorologisk institutt weather API for additional information such as outdoors temperature and weather forecast in the GUI.
• Flask for server deployment + Pagekite for HTTPS tunneling to control the app through an Alexa Smart Home Skill.

Physical configuration

The BME680 sensor is wired as follows:

• Pi 3V3 to sensor VIN
• Pi GND to sensor GND
• Pi SCL to sensor SCK
• Pi SDA to sensor SDI

The 4-channel relay module is wired as follows:

• Pi 5V to module VCC
• Pi GND to module GND
• PI GPIO 17 to module IN1 (water valve control)
• PI GPIO 22 to module IN2 (fan lo-speed control)
• PI GPIO 23 to module IN3 (fan mi-speed control)
• PI GPIO 27 to module IN4 (fan hi-speed control)

For a graphic reference, refer to the schematic below.

Amazon Alexa configuration

In order to use the Alexa portion of the project, you must build your own Alexa smart home skill. You could follow the official guide on Steps to Build a Smart Home Skill and use the code I implemented for my own skill, found in here.

Create a new account on pagekite (they have a free trial) to enable HTTPS tunneling and do the following configuration:

• In the index.js file for AWS lambda, update the constant tok with a unique secret token.
• In the project, rename server_config.json_template to server_config.json (located in assets/config) and assign the values tunnel, port and token to the your new pagekite server, pagekite port and secret token created in the previous step, respectively.

Database details

An internal SQLite database is used to store outdoor and indoor status for future data analysis. The items stored in the DB are:

• Temperature, humidity, air pressure, gas resistance and air quality, coming from the BME680 sensor.
• Current state of the GUI such as target temperature and set fan speed.
• Latitude, longitude, outdoor temperature, humidity, pressure, forecast condition, wind speed, wind direction and precipitation percentage. All coming from the weather API.

Installation and usage

For a quick run of the project, clone the repository and execute the commands below at the root directory. It is recommended to use a virtual environment created with virtualenv.

pip install -r requirements.txt
python3 tests/main_test.py

Additional resources

To see the SmartCoil in action, please refer to the following video:

You could also read this article for more details on how I built this project at home.

License

MIT