This is a Ruby-on-Rails app that runs on a raspberry pi to monitor and control my wood stove. It monitors the temperature with an infrared sensor. It uses a relay board to turn the stove's blower fan off and on according to limits I define through the web interface. This feedback loop helps regulate the stove's temperature and keeps the fire burning in an efficient, safe range. I get push notifications if it crosses certain limits (like if it's too hot and I need to cool it off, or once the fire has died down and it's the perfect time to reload it). The web interface isn't that polished, but it's really useful!
Features:
- Saves temperature readings every minute
- cron jobs controlled via https://github.com/javan/whenever
- Web interface for viewing historical temp readings (it's barebones)
- Temperature monitors configurable via web interface
- Send a push notification via Pushbullet when it's crossed
- Turn the stove's blower fan off/on when it's crossed (helps regulate stove temperature)
- Multiple parameters for tuning temp sensor readings, if they're too high/low
- Helps accomodate different sensor positions (on top of the stove, pointed at the stove sidewall, further away, etc.)
- Input field to save confirmed readings, so you can record temperatures from a different thermometer by hand, then tune parameters to make your readings align with them.
- Auto refresh when new temperature is recorded
- Tab icon and title change to reflect the stove's temperature
Demo video: https://www.youtube.com/watch?v=sp3rUNzEKyg
Setup rails on your raspberry pi
# https://joelc.io/install-ruby-rails-raspberry-pi
# Slow official way
sudo apt-get install screen
screen bash
sudo apt update
sudo apt install -y curl build-essential zlib1g-dev libreadline-dev libssl-dev libxml2-dev
gpg --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB
curl -sSL https://get.rvm.io | bash -s stable --rails
# ctrl+A D to disconnect but leave it runnning
# ctrl+D to kill it
# screen -r # to reconnect
Setup redis, if you want the page to automatically refresh to show the latest temperature data (using ActionCable):
sudo apt install redis-server
redis-cli ping # verify it worked
Seed some data:
bin/rails db:migrate RAILS_ENV=development
# When my temp sensor was pointed at the stove sidewall (where the heat had to go through a lot of
# material / firebrick), I was using a dynamic_temp_factor (deprecated) of 16.
# Once I moved the temp sensor to point at the top of the stove, I set dynamic_temp_factor to zero with great success.
# However, it's helpful to use a value of about 5 for dynamic_down_temp_factor, so that your fan turns off quicker
# if you closed the damper too much and your fire just went out.
# But it's good to keep dynamic_up_temp_factor set to zero, so that the stove doesn't cool itself off too early
# before the surface has warmed up. It's completely fine to have a ROARING fire as the stove is heating up.
Settings.create!(static_temp_factor: 1.15, static_temp_offset: 75, dynamic_down_temp_factor: 5, dynamic_up_temp_factor: 0, max_rate_adjustment_delta: 100)
TempMonitor.create!(upper_limitf: 500, lower_limitf: 60)
Set PUSHBULLET_ACCESS_TOKEN env variable, grab one from https://www.pushbullet.com/#settings. Needed for notifications
sudo vi /etc/profile
export PUSHBULLET_ACCESS_TOKEN=asdf
:wq
# Test via rails console, TempMonitor.last.send_push_notification!('title here test', 'body')
Start the rails server:
bundle install
rails s -b 192.168.1.188
# or in the background
screen rails s -b 192.168.1.188
# then ctrl+A D
Or start the rails server automatically on boot:
# from
# https://forums.raspberrypi.com/viewtopic.php?p=921354
# https://forums.raspberrypi.com/viewtopic.php?t=202216
cd /etc/systemd/system/
sudo vi woodstove.service
[Service]
WorkingDirectory=/home/pi/wood-stove-rails
ExecStart=/bin/bash -lc 'rails s -b 192.168.1.188'
Restart=always
StandardOutput=syslog
StandardError=syslog
SyslogIdentifier=woodstoverails
User=pi
Group=pi
[Install]
WantedBy=multi-user.target
:wq
sudo chmod u+rwx /etc/systemd/system/woodstove.service
sudo systemctl enable woodstove # launch it at boot
sudo systemctl start woodstove # launch it right now
Control cron jobs for recording temp info (and processing monitors/notifications):
# Turn them on
bundle exec whenever --update-crontab --set environment='development' # see config/schedule.rb
# Turn them off
bundle exec whenever --clear-crontab
Start ngrok automatically on boot:
cd /etc/systemd/system/
sudo vi ngrok.service
[Service]
WorkingDirectory=/home/pi/
ExecStart=/bin/bash -lc './ngrok http 192.168.1.188:3000 --basic-auth="username_here:password_here"'
Restart=always
StandardOutput=syslog
StandardError=syslog
SyslogIdentifier=ngrok
User=pi
Group=pi
[Install]
WantedBy=multi-user.target
:wq
sudo chmod u+rwx /etc/systemd/system/ngrok.service
sudo systemctl enable ngrok # launch it at boot
sudo systemctl start ngrok # launch it right now
Enable i2c and friends
# Setup i2c. Chapter 7 of freenove manual. https://freenove.com/tutorial.html "Configure I2C and Install Smbus"
sudo raspi-config
# Choose “Interfacing Options” then “P5 I2C” then “Yes” and then “Finish” in this order and restart your RPi.
lsmod | grep i2c # check whether the I2C module is started:
#i2cdetect -y 1
#i2cdump -y 1 0x5a w
pip install smbus
Wire up the MLX90614 temp sensor. The sensor has labels "SDA" and "SCL". I happen to have these hooked up to SDA1 and SCL1 (see port in lib/read_temp.py). Ground goes to ground, and VIN goes to a 5V output. The raspberry pi pinout diagrams you find on google are from the perspective of looking down on the PI. For understanding the orientation of the extension ribbon cable, imagine it's connecting two PIs side by side on the same surface. If you get this backwards, the sensor will get quite hot.
Other useful links regarding this sensor:
- https://www.amazon.com/gp/product/B071VF2RWM/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
- https://olegkutkov.me/2017/08/10/mlx90614-raspberry/
- https://www.raspberrypi.org/forums/viewtopic.php?t=17738
For controlling the stove's blower motor, cut an AC extension cord in half, then wire a relay like you would a light switch. See app/models/relay_service.rb for notes on GPIO pin numbers. Here's the relay board I used: https://www.amazon.com/gp/product/B01G05KLIE/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
- Run the test suite on your laptop:
bundle exec rspec - SSH into your raspberry pi
- cd into the folder where you've cloned the repo
git pull
This is a side project I'm not investing much time into. Feel free to open an issue and discuss if you really want to contribute something.