SensorHub

SensorHub

Table of Contents

• SensorHub
  • Table of Contents
  • About
  • Image sources
  • Setup
  • Device modes
  • Bluetooth
  • Measurement
  • History
  • Maintainer

About

Solar-powered, low energy environment sensor node with WiFi interface. The device will measure the following parameter:

• Temperature (with a MCP9808)
• Humidity (with a BME680)
• Pressure (with a BME680)
• Gas resistance (with a BME680)
• Ambient light (with a BH1726)
• UV (with a VEML6070)

The whole device is designed for low power operation and for a solar panel as current source. A backup battery will be used to buffer the sun-free time during the night or on cloudy days. This battery will be charged by an integrated solar-charging circuit.

The integrated WiFi is used to transmit the data as an MQTT message to a broker (i. e. a Raspberry Pi). The included Qt application for the Raspberry Pi can be used to visualize and record the received data.

Please visit the project site or write me an e-mail when you need additional informations or if you have any questions.

Image sources

• Language Icons
• Icons8
• Qt project

Setup

• You have to use the Particle CLI or the Particle App to setup your WiFi credentials in the microcontroller module before you can use the software.

$ particle usb start-listening
Done.

$ particle serial wifi
? Should I scan for nearby Wi-Fi networks? (Y/n) y
? Should I scan for nearby Wi-Fi networks? Yes
? SSID ...
? SSID ...
? Security Type (Use arrow keys)
? Security Type ...
? Cipher Type (Use arrow keys)
? Cipher Type ...
? Wi-Fi Password ...
? Wi-Fi Password ...
Done! Your device should now restart.

• Download a bluetooth app for your smartphone (i. e. nRF Connect).
• Make sure that your microcontroller module runs at least firmware version 1.5.2.
• Optional: Build the firmware from the soures in software/SensorHub by using Visual Studio Code and the Particle Workbench.
• Power up the SensorHub and flash the firmware from software/release by using the Particle CLI.
• Hold the MODE button of the microcontroller module to enter the setup mode.
• After entering the setup mode the RGB LED of the device will lights up red.
• Open the app and connect your smartphone with the SensorHub. When the connection is successful the RGB LED of the SensorHub starts to blink green until you close the connection or a IP address of the MQTT broker was transmitted successfully.

Device modes

The SensorHub use the RGB led of the microcontroller module to display his current state. Each state is encoded in a blink pattern which begins with a 3 seconds group color.

The group color is followed by the error code which is encoded with a white flashing of the RGB LED. Each flash has a duration of 1 second.

The current device error is also printed over the serial interface of the microcontroller module or is published over the MQTT tag sensorhub/errors (this required valid network settings).

Bluetooth

The firmware use the following UUIDs for the bluetooth low energy service:

Measurement

After a successful configuration and initialization the device will enter the sleep mode. The microcontroller is woken up every three minutes to read in new data from the sensors. After a successful read of the sensors the data gets packed in a JSON structure and published by using the MQTT protocol. The firmware uses the topic sensorhub/weather to publish the sensor data in the network. The JSON object uses the following structure:

{
  "Temperature": "23.0",
  "Ambient light": "1000.0",
  "UV": "7",
  "Pressure": "1004",
  "Humidity": "44.0",
  "Gas resistance": "20000",
  "Gas valid": "0",
  "IAQ": "97.5",
  "IAQ valid": "0",
  "Solar": "1.2",
  "Battery": "3.3"
}

History

Maintainer

• Daniel Kampert