Digoo temperature network

1-README.md

What's going on?

Some sensors collect data, transmit it to a radio, which is picked up by a reciever machine, which writes it into some storage for display.

Sensors

The sensors are called "Digoo DG-R8H R8H 433MHz Wireless Digital Hygrometer Thermometer Weather Station Outdoor Sensor for TH11300 TH8380 TH1981".

For these, I paid $3.82/item delivered in 2019. The price appears to have doubled in 2022.

• My order, no longer available: https://www.aliexpress.com/item/32845484171.html
• Visually similar: https://www.aliexpress.com/item/1005001993444509.html

They take 2xAAA batteries, and transmit a rtl_433 compatible signal. It identifies them as Nexus-TH. Each devicce has a one-byte(?) device ID, and a 3-way "channel" switch. All of my eight devices have different device ids, which is reasonably likely for <<20 devices, so I can ignore the channels.

Radio

Radio reception is with a rtl-sdr (RTL2832U), I use a NooElec NESDR SMArt to allow me to play with antenna, but it is completly unnecessary for this application.

These cost around $48 (2022) with an antenna. You may also want a good-quality (grounded) USB extension cable if you want to locate the radio slightly away from the recieving device.

Reciever

rtl_433 is run on an Ubuntu "nl40" microserver which runs 24/7.

It is configured to write mqtt to a local mosquitto server:

/usr/local/bin/rtl_433 -F mqtt:,devices,retain=1

See the systemd unit below for the full config.

Remainder of the stack

This mqtt can then be consumed by home-assistant, to drive automation and alerting, or can be fed into telegraf/influx/grafana for a nicer storage and graphing experience, like in the neohub-mqtt docs.

See below for an example telegraf config.

2-systemd.service

# /etc/systemd/system/rtl-433.service

[Unit]
Description=rtl-433

[Install]
WantedBy=multi-user.target

[Service]
DynamicUser=yes
Group=plugdev

ExecStart=/usr/local/bin/rtl_433 -F mqtt:,devices,retain=1

Restart=on-failure
RestartSec=10s

#[Hardening]
ProtectSystem=strict
ProtectHome=yes
ProtectKernelTunables=true
ProtectControlGroups=true
ProtectKernelModules=true
#PrivateDevices=true
NoNewPrivileges=true
CapabilityBoundingSet=

3-telegraf.toml

[[inputs.mqtt_consumer]]
  servers = ["tcp://127.0.0.1:1883"]
  topics = ["rtl_433/urika/devices/Nexus-TH/+/+/battery_ok","rtl_433/urika/devices/Nexus-TH/+/+/temperature_C","rtl_433/urika/devices/Nexus-TH/+/+/humidity"]
  name_override = "nexus"

  topic_tag = ""

  data_format = "value"
  data_type = "float"

  [[inputs.mqtt_consumer.topic_parsing]]
    topic = "rtl_433/urika/devices/Nexus-TH/+/+/+"
    tags = "_/antenna/_/_/channel/device_id/kind"

  [[processors.pivot]]
    tag_key = "kind"
    value_key = "value"

  [[processors.enum]]
    [[processors.enum.mapping]]
      tag = "device_id"
      dest = "room"
      [processors.enum.mapping.value_mappings]
        69 = "kitchen"
        13 = "lounge"
        37 = "bedroom"