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What is Sensus?

Sensus is a ultra-lowpower, Homeassistant-compatible environment and plant sensor. It started as a plant health monitoring sensor but ended up being a more general-purpose environment sensor with optional addons, one of which is the Plant Health Monitoring Addon.

Main Features

  • Measures Temperature🌡️, Relative Humidity 💧, Illuminance ⛅ and Battery Voltage 🔋
    • 🌱 Additional Plant Addon also adds Soil Temperature and Soil Moisture
  • Homeassistant compatible out of the box, thanks to the BTHome data format 1
  • Transmits data via Bluetooth Low Energy and USB 🔌
  • Compatible with BLE4.0+ adapters
  • 100m of range when transmitting data via Bluetooth 📶
  • Powered either via USB-C or a CR2032 battery
  • Ultra-low power consumption, ~1 year battery life when powered from a high-quality CR2032 battery 2
  • RGB status LED 🚦
  • sensus-cli command line interface that can be used to:
    • Log real-time data via USB and save to a CSV file
    • Log real-time data via Bluetooth and save to a CSV file not yet implemented
    • Configure parameters such as time between measurements, Bluetooth name, LED behavior
    • Power-safe firmware updates via USB and BLE 3
    • Read device information such as firmware version and MAC address/serial number
  • Optional magnetic 3D printed case with plexiglass window available

Specifications - Sensus


All accuracy related specifications assume the device is functioning within the recommended operating temperature range of -10°C - 45°C (14°F - 114°F)

Operating voltage 1.7V - 3.6V
Supply current (while on battery) 24μA typ.
Operating temperature -10°C - 45°C (14°F - 114°F)
Operating relative humidity any %

Temperature and RH sensor

Sensor Sensirion SHTC3
Temperature range -40 - 125°C (-40 - 257°F)
Typical temperature accuracy ±0.2°C (±0.36°F)
Maximum temperature accuracy ±0.5°C (±0.9°F)
Humidity range 0 - 100%
Typical relative humidity accuracy ±2%

Illuminance sensor

Sensor Texas Instruments OPT3001
Measurement range 0 Lux - 83865.6 Lux

Specifications - Soil Probe

Probe soil moisture sensor

Sensor Custom RC oscillator
Type Capacitive; non-contact
Measurement frequency 10kHz - 2MHz
Calibration Calibrateable via CLI

Probe temperature sensor

Sensor Texas Instruments TMP112
Measurement range -40 - 125°C (-40 - 257°F)
Typical accuracy ±0.5°C (±0.9°F)
Maximum accuracy ±1.0°C (±1.8°F)

Commonly asked questions

Is the device waterproof?

The soil probe is waterproof, however the main control unit (the rectangular PCB) is not due to the limitations of a 3D printed case. I recommend to exercise caution with the main unit and avoid anything more than light splashes, even though it might be fine.


I did test the Sensus in outside conditions for long periods of time and with occasional water spraying on the main unit and it still appears to function, however I can't recommend you do the same. You can, but it's on your own risk.

  1. See the official Homeassistant BTHome integration page for more information.
  2. Battery life can be increased slightly (or decreased) using the command-line interface to raise (or lower) the time between measurements.
  3. BLE firmware updates are coming soon.