A multitier modular collection of software meant to work on a Raspberry Pi Zero W to control an older non-smart thermostat. Any other pi would likely work just fine.
While a raspberry pi thermostat isn't exactly novel, this particular project was designed with extensibility in mind, so you can easily build any service to communicate with your thermostat. The API is exceedingly simple and easy to use. Two relays superficially control an older thermostat by simulating button presses.
Easy Setup
Pasting the line below into a fresh terminal on the pi will do all the software setup for you.
sudo bash -c 'apt update -y && apt upgrade -y && apt install redis-server openjdk-8-jre wiringpi nodejs npm git -y && npm i -g npm@latest && npm i -g serve --save' && cd ~ && rm -rf ~/RPI-Retrofit-Smart-Thermostat && git clone https://github.com/geektechniquestudios/RPI-Retrofit-Smart-Thermostat && cd /home/pi/RPI-Retrofit-Smart-Thermostat/CCTA-React-Client && npm i && npm run-script build && (crontab -l ; echo "@reboot java -jar /home/pi/RPI-Retrofit-Smart-Thermostat/ccta-1.0.0.jar") | crontab - && (crontab -l ; echo "@reboot sudo serve -l 80 -s /home/pi/RPI-Retrofit-Smart-Thermostat/CCTA-React-Client/build") | crontab - && echo "Success! Restart the pi and your server will be online. You can see it by typing the ip address of the pi into a web browser."If you experienced any issues, check out the troubleshooting section at the bottom of the readme.
Advanced Setup (optional alternative)
In case you'd prefer to individually install your dependencies, you'll need the following:
-
a redis server running on the pi
sudo apt install redis-server -
a java 1.8+ jre
sudo apt install openjdk-8-jre -
node
sudo apt install nodejs -
npm
sudo apt install npmnpm i -g npm@latest -
serve
sudo npm i -g serve --save -
wiringpi
sudo apt install wiringpi
You'll need to build the react project before serving it. You can do that by navigating into the ccta-react-client folder and running
npm i
npm run-script build
If you'd like the pi to automatically start the spring boot and react servers on boot, you'll probably want to add them to a crontab. You can do that by typing
crontab -e
and appending the following lines to the end of the file
@reboot java -jar /home/pi/RPI-Retrofit-Smart-Thermostat/ccta-1.0.0.jar
@reboot sudo serve -l 80 -s /home/pi/RPI-Retrofit-Smart-Thermostat/CCTA-React-Client/build
This system operates on the pretense that your pi has the reserved address 10.0.0.6. Your LAN router IP might be 192.168.1.1 or something else. If you can't reserve 10.0.0.6 for your pi, you may have to change the IP addresses in code or change your local ip configuration to get this working in your environment.
While figuring out what GPIO pins to use to control the relay, reference the pi4j wiring documentation. It may vary from board to board, so carefully ensure you have the correct wiring. Based on wiringpi's wiring and not the pi's header numbering, this code uses gpio pin 0 for temperature down, and gpio pin 1 for temperature up.
Once you have everything installed and your IP address reserved, restart your pi. You should be able to access the pi over your LAN by typing 10.0.0.6 into a web browser. As a convenience you can change this to thermostat/ if your router supports local DNS; alternatively, use may consider dnsmasq.
AC units have a 24v AC wire (red | R) and a common ground (blue or black | C). You can get a transformer to power the pi for 5 or 10 dollars on Amazon. I bought this one (affiliate link) because it has a potentiometer, allowing you to control the output voltage. Pis can be powered by connecting 5v DC power to the respective positive and negative rails of the board.
Fortunately, removing a bathroom mirror leads directly into the wall behind my thermostat. The pi changes the temperature by shorting the circuit that the button normally bridges when pressed.
- There is a 10 second debounce buffer on the update temperature action if multiple requests are sent, otherwise there is a 3 second buffer. Any input you give the thermostat intentionally takes a moment to execute. You can change these values in the spring boot thermostat controller.
- The react native app is very simple and easy to modify. It is only about 80 lines of code and serves more as a proof of concept, whereas I use the reactjs web client on a daily basis.
If "Easy Setup" fails
If you need to rerun the easy setup command after it successfully completes, you should check your crontab file by typing crontab -e. Ensure you don't have the same commands repeated over and over from running the setup script repeatedly.
If you get a message like
no crontab for pi
then you need to create a crontab file by typing crontab -e. It'll open in your default terminal editor. Ensure the following lines are at the end of the crontab.
@reboot java -jar /home/pi/RPI-Retrofit-Smart-Thermostat/ccta-1.0.0.jar
@reboot sudo serve -l 80 -s /home/pi/RPI-Retrofit-Smart-Thermostat/CCTA-React-Client/buildSave, quit, and restart the pi. If you have any additional issues, please feel free to open an issue on this project or shoot me a message. I'll try to respond in a timely fashion.
If your relays don't work
The relays I used for this project are closed circuit by default. If you need or want to use relays that work in the opposite fashion, take a deep breath and rub your eyes. You can look in the Spring Boot Server and find the TemperatureController.java file in the src folder. Invert the values of the pin states on lines 19, 23, 121, 123, 132, and 134. To be extra clear, on the aforementioned lines, everywhere it says PinState.LOW, or PinState.HIGH, exchange one for the other. Rebuild the jar file with mvn clean install in the project directory. Then send the generated jar file to the pi directory /home/pi/RPI-Retrofit-Smart-Thermostat/ccta-1.0.0.jar, finally restart the pi. If this seems like a lot, send me a message and I'll do my best to help. If anyone asks me, I'll probably just build another jar file to make it easier. HMU, or I won't know I need to get on this, although I will eventually get to it.
Thanks for checking out my work. I really appreciate any engagement!