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

https://homesmartmesh.discourse.group/c/projects/thread-sensortag/13

Overview

from https://www.homesmartmesh.com/docs/microcontrollers/nrf52/thread_sensortag/

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

Schematics repo : https://github.com/HomeSmartMesh/nrf52_thread_sensortag

Application

Zephyr firmware repo : https://github.com/HomeSmartMesh/sdk-hsm-sensortag

Produced udp packets from the nRF52840 are directly text json packets

This is the script that converts the ipv6 udp packets to MQTT posts

https://github.com/HomeSmartMesh/raspi/blob/master/py/thread_tags/thread_tags.py

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')
    log.info(f"'{topic}' => {payload}")
    clientMQTT.publish(topic,payload)

Low power performance

measured with the PPK-II

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

First Produced version v1.0, now v1.1 exist with added LED