Openthread Sensor Tag

Open Design Ultra Low Power Sensor Tag for light, temperature, humidity and pressure. openthread on Zephyr with json to MQTT and Grafana

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Ships from Germany
The schematics are open source and ready production gerber files are provided. The firmware also opensource with a full stack innovative with simplicity text based udp packets with minimal python server side for MQTT influxDB and Grafana connection. The SensorTag deep sleeps at 3.19 uA and estimated to last x3 years with 20 sec report period of all sensors

Free Technical support available for those who want to produce and adapt the firmware. The sensor Tag project has its own category on the new Home Smart Mesh forum

I sell on Tindie



The Thread Sensor Tag is running on a nRF52840 Microcontroller Module (MS88SF2 from Minew). It uses a Light sensor to detect light in lux and a multi functional sensor for pressure, temperature and humidity. See details below:

  • nRF52840 on a MS88SF2 module. 
  • Light sensor VEMLS6030 @0x48
  • MS8607 with relative humidity @0x40, pressure and temperature @0x76
  • Reset button P0.18 and user button SW0 P1.09
  • i²C bus scl P1.13 and sda P1.15
  • RGB LED P0.04 P0.06 and P0.08

Schematics repo :


The nRF52840 wakes up every 20 seconds, collects the values for temperature, pressure, humidity and light and sends them via UDP package into the Open Thread network which it connects to. We chosed to use UDP packets because this is the fastest way of transmitting the data which safes time and therefor energy. For example MQTT or Matter would use more energy because it takes longer due to the bigger payload size.

The Zephyr firmware repository can be found here:

To make a use of the UDP packets we created a script which translates the ipv6 UDP data into a JSON based MQTT message. This script can run as a service on a Raspberry Pi:

This is all the python code that has to run on server side :

while True:
    data, addr = sock.recvfrom(1024) # buffer size is 1024 bytes
    message = data.decode("utf-8")
    parts = message.split("{")
    topic = friendly_topic(parts[0])
    payload = '{'+parts[1].rstrip('\n')"'{topic}' => {payload}")

Low power performance

measured with the PPK-II

PeriodAverage Current
deep sleep3.19 µA
sensors acquisition54 µA
wakeup cycle 1.7 sec including RF125 µA

Available on Tindie

  • Home Assistant MQTT Discovery integration

    Mirko03/01/2023 at 14:29 0 comments

    Finally we have implemented and integrated the Thread Sensor Tag to be used in Home Assistant! Look how beautiful it is:

    Once you have the MQTT integration installed and setup and a Thread Sensor Tag connected it will be automatically detected with all the values in the image (Voltage is of course from the battery)

    Also multiple devices can be detected and be used.

  • Thread Sensor Tag running on Solar (outdoors)

    Mirko02/22/2023 at 09:33 0 comments

    I tested the solar-version of the device and the solar panel short circuit current indoors was only around 0.6mA which is not enough to really charge the battery. I moved it outside on the balcony and now it is charging and running perfectly. 

    The white stuff in the image is just some trash to move the solar panel and the Thread Sensor Tag up and against the glass ;)

  • Thread Sensor Tag with a AEM10941 Solar Harvesting IC

    Mirko02/16/2023 at 09:58 0 comments

    We tried to run the Thread Sensor Tag with a AEM10941 Solar Harvesting IC (Module can be found here: ) from E-peas (see image below) and a small 45x45 4.5V Solar Panel. This was supposed to harvest energy inside a building but apparently it did not work out as expected. Somehow the battery voltage droped lower and lower even with brighter light. Not sure whats the cause of it and we have to investigate more but the idea was that this device will never need a battery change again!

View all 3 project logs

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