Use a Raspberry PI connected to one or more temperature sensors to send the results to a MQTT server.
Install the program into opt/ThermoPI-Furnace or any suitable location. (Some people like /usr/local/bin instead of /opt) Make sure the username that is going to be running this script has access to the files and is able to get at python and anything else needed and used here-in.
You will need to rename the file MYsecretsSample.yaml to MYsecrets.yaml. Edit the contents of the new MYsecrets.yaml to match your MQTT & Home Assistant installation and requirements. You will also need to supply the full path to the secrets file in the Get the parameter file section of this python code around line 225.
This program grabs the 2nd half of the MAC address to use as the device ID. This only works consistently when there is only 1 Ethernet interface configured or you have your multiple interfaces cloned to the same MAC Address. For instance if it boots from WIFI, it will grab that MAC, and if it uses the Ethernet cable or a USB interface, it will grab that MAC. You get my point. This can be avoided by hard coding the DeviceID with the random and unique number of your choice. Also I have not tested this with IP6 addresses. If you have solutions to any of this, please share.
Here is a good reference on setting up a program to run from systemd. Use it to get familiar with the process.
How-To Geek on 'Startup With Systemd'
To run the program at boot in order to get constant readings, there is the ThermoPIFurnace.service to run this as a service with load-service.sh there to set it up as a service.
The load-service.sh script will stop and scratch reload the service from the local repository (Once you get all the permissions happy).
The furnRestart.sh is the script to quickly restart the process if needed during troubleshooting. I found it helpful.
Program requirements (as written): (Feel free to fork it & update the obsolete DHT Libraries to CircuitPython DHT Libraries and dropping me a merge request...)
- Python 3.6 or better
- PyYAML For reading the YAML parameter file
- pigpio For reading the Thermocouples (MAX6675)
- max6675 Thermocouple demux code
- W1ThermSensor For 2 wire temp sensors (DS18B20)
- Adafruit_DHT For temp / humid sensors (AM2302)
- paho-mqtt For MQTT broker connection
If you have any questions, comments or additions be sure to add an issue and bring them up on my Discord Server:
Suggested image for your PI is the latest 32bit lite. You can use the regular load if you are using the PI for other things, but none of the gui functions are needed. The Raspi imager software also lets you set up name, password, timezone, and start the ssh server on image load, so do those things. After it boots log in and update-upgrade it to get all the packages up to date. Reboot...
Use raspi-config to set up localization. In the 'Interface Options' enable 'Remote GPIO'. You may want to add other things.
sudo apt-get update
sudo apt-get install python3-pip git pigpio python3-gpiozero python3-pigpio
sudo python3 -m pip install --upgrade pip setuptools wheel
sudo systemctl enable pigpiod
sudo systemctl start pigpiodsudo pip3 install Adafruit_DHT PyYAML w1thermsensor paho-mqttNOTE: Be sure to note the serial numbers of the sensors and know where each sensor is physically located.
sudo nano /boot/config.txtAdd this line at the end. I am using GPIO23. You can use another GPIO but the GPIO numbers (not the header pin numbers) must match where the dallas sensors are connected.
If you are using the internal pull-up (NOT Recommended) you can eliminate the ',pullup=0' part.
dtoverlay=w1-gpio,gpiopin=23,pullup=0
Then reboot:
sudo rebootThen install the 1-wire sensors and make sure they are there.
sudo modprobe w1-gpio
sudo modprobe w1-therm
ls -la /sys/bus/w1/devicesYou should see something like this with different numbers:
28-3c01f0965030 28-60d70d1864ff w1_bus_master1
The actual serial number(s) to remember is everything after the '28-'.
cd /opt
sudo mkdir ThermoPI-Furnace
sudo chown [your user name here] ./ThermoPI-Furnace
sudo chgrp [your user name here] ./ThermoPI-Furnacecd /opt
git clone https://github.com/SirGoodenough/ThermoPI-Furnace.git
cd ThermoPI-FurnaceBased on the MYsecretsSample.yaml as a starting point, make your own. You will need to have figured out your 1-wire sensor serial numbers and know your MQTT login information to complete this section.
cp MYsecretsSample.yaml MYsecrets.yaml
nano MYsecrets,yamlTroubleshoot as needed. 'MQTT Update result 0' means that part of the loop went well. After you get it to loop thru a couple of times, use 'ctrl-c' to stop it and continue to next step.
/usr/bin/python3 /opt/ThermoPI-Furnace/furnace.pyLong term use of this software will make too many writes to the SD card, filling it up and wearing out the card. Therefore > /dev/null 2>&1 has been added to the thermoPIFurnace.service file to reduce writes to the SD card. For Troubleshooting you MAY want to turn this off temporarily. Just remove those characters from this file and all will be logged. Be sure to turn this on or off as you desire before running this section, or if you change that file re-run this section. Frankly I prefer stopping the application sudo systemctl stop thermoPIFurnace.service and running it manually like above for troubleshooting. Then restarting it when done sudo systemctl start thermoPIFurnace.service.
The line 'User=XXX' in the file thermoPIFurnace.service needs to be edited to match the username that will be running the application. Running as Root is HIGHLY DISCOURAGED.
/opt/ThermoPI-Furnace/load-service.shYou should see similar to this:
furnacepi@furnpi:/opt/ThermoPI-Furnace $ ./load-service.sh
Stopping ThermoPI-Furnace
Failed to stop thermoPIFurnace.service: Unit thermoPIFurnace.service not loaded.
Copy file over
Change permissions on new file
Reload the systemd daemon
Enable the new service
Created symlink /etc/systemd/system/multi-user.target.wants/thermoPIFurnace.service → /lib/systemd/system/thermoPIFurnace.service.
Start the new service
Check that the new service is running
● thermoPIFurnace.service - ThermoPI-Furnace Status Reader
Loaded: loaded (/lib/systemd/system/thermoPIFurnace.service; enabled; vendor preset: enabled)
Active: active (running) since Sun 2023-01-22 14:02:40 CST; 7s ago
Main PID: 1267 (python3)
Tasks: 3 (limit: 1596)
CPU: 1.242s
CGroup: /system.slice/thermoPIFurnace.service
└─1267 /usr/bin/python3 /opt/ThermoPI-Furnace/furnace.py > /dev/null 2>&1
Jan 22 14:02:40 furnpi systemd[1]: Started ThermoPI-Furnace Status Reader.
After it's running head to home assistant devices 
ThermoPI Furnace. That is your list of sensors which you can do with as any other sensor.
This is roughly the circuit used with this program:
- Discord WhatAreWeFixingToday
- What are we Fixing Today Homepage
- YouYube Channel Link
- What are we Fixing Today Facebook page
- What are we Fixing Today Twitter
If your device connects to mains electricity (AC power) there is danger of electrocution if not installed properly. If you don't know how to install it, please call an electrician.
Remember: SAFETY FIRST. It is not worth the risk to yourself, your family and your home if you don't know exactly what you are doing. Never tinker or try to flash a device using the serial programming interface while it is connected to MAINS ELECTRICITY (AC power).
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