A repo to keep the code for the various not-quite-the-same devices we use to measure temperature in the house. These are almost entirely Raspberry Pi 3s with DS18B20 sensors, but there are also some Pi 2s, a Pi zero and a Pi3 wearing a SenseHat. The temperature readings are published to MQTT and you'll also find the script that writes to PostgreSQL.
You will need the W1ThermSensor library: sudo apt-get install python3-w1thermsensor
Clone the repo, run pip3 install -r requirements.txt in the temperature_to_mqtt directory. Then set up a script to automatically run the appropriate script for your pi when it boots (something like this https://www.raspberrypi-spy.co.uk/2015/10/how-to-autorun-a-python-script-on-boot-using-systemd/)
My script is /lib/systemd/system/temperature.service and it looks like this:
[Unit]
Description=Temperature Monitoring Service
After=multi-user.target
[Service]
Type=idle
ExecStart=/usr/bin/python3 /home/pi/code/temperature-sensors/temperature_to_mqtt/temperature_sense_hat.py
[Install]
WantedBy=multi-user.target
The server part will listen to MQTT and the messages from all the sensors, and write the values to a postgresql database.
The database needs a table called temperature_reading which looks like this:
house_metrics=> \d temperature_reading
Table "public.temperature_reading"
Column | Type | Modifiers
------------------------+-----------------------------+--------------------------------------------------------------------------------------
temperature_reading_id | integer | not null default nextval('temperature_reading_temperature_reading_id_seq'::regclass)
sensor_id | character varying(100) | not null
created_at | timestamp without time zone |
value | real |
units | character varying(10) |
Indexes:
"temperature_reading_id" PRIMARY KEY, btree (temperature_reading_id)
The code is in /mqtt_to_postgres/postgres.py and this script needs the environment variable PGPASSWORD when it is run. Run pip3 install -r requirements.txt in the directory to get the dependencies, then run the script like this:
PGPASSWORD=secret python3 postgres.py
As for the sensor, this code wants to live under systemd or similar since if any readings are missed, they can't be recovered.