Raspberry Pi Temperature and Humidity Server

Simple NodeJS server and SQLite3 logger for the DS18B20 digital temperature sensor on the Raspberry Pi. Based on PiThermServer by Tomas Holderness.

Description

A NodeJS server for the DS18B20 GPIO temperature sensor and the Acurite 06009RM temperature/humidity sensor on the Raspberry Pi. The DS18B20 sensor is accessed using the w1-gpio and w1-therm kernel modules in the Raspbian distro. The Acurite sensor transmits at a nominal 433.92 MHz using amplitude-shift keying, and is received via an R820T-based SDR receiver and the rtl_433 software-defined radio code. The server parses data from the sensors and returns the temperatures and humidity and a Unix time-stamp in JSON format, this is then written to an SQLite database on the Pi. A simple front-end is included and served using node-static, which performs ajax calls to the server/database and plots DS18B20 temperature, Acurite temperature, derived dewpoint temperature, and Acurite humidity from a time-series, using the highcharts JavaScript library.

Files

• load_gpio.sh - bash commands to load kernel modules
• server9.js - NodeJS server, returns temperature as JSON, logs to database and serves other static files
• thlog.htm - example client front-end showing time-series from database records
• build_database4.sh - shell script to create database schema
• run_rtl433.sh - runs the rtl_433 demodulator to update the Acurite readings in temp.json
• thserver.service - starts the server on boot and restarts it if necessary

Dependencies

• NodeJS
• SQLite3
• node-sqlite3
• node-static
• rtl_433, which in turn depends on rtl-sdr.

Install/Setup

1. Run npm install in this directory.
2. Install SQLite3, node-sqlite3, node-static, rtl-sdr, and rtl_433.
3. Run load_gpio.sh script as root to load kernel modules for the DS18B20 sensor.
4. Run the build_database4.sh script to create piTempHum.db. Note this wil drop any existing database of the same name in the directory.
5. Open server4.js and edit line 45 to read the serial number of your DS18B20 sensor in /sys/bus.
6. Copy thserver.service to /etc/systemd/system/.
7. Run sudo systemctl enable thserverto enable the service.
8. Make run_rtl433.sh executable: chmod +x run_rtl433.sh.
9. Edit crontab to add the following to run rtl_433 every 5 minutes for 45 seconds to update temp.json:
   MAILTO=""
 */5 * * * * /home/pi/PiThermServer/run_rtl433.sh > /dev/null<br>
10. Reboot the Pi. Wait a minute or two.
11. Open a web browser on the Pi and go to 'http://localhost:8087/temphum_logr4.htm' to see a plot logged temperature.

References

http://www.cl.cam.ac.uk/freshers/raspberrypi/tutorials/temperature/
https://github.com/talltom/PiThermServer
http://osmocom.org/projects/sdr/wiki/rtl-sdr
https://github.com/merbanan/rtl_433
https://github.com/mapbox/node-sqlite3
https://github.com/cloudhead/node-static