This repository holds the migration of my earlier Arduino weather station implementation https://github.com/kbarrell/Arduino-WeatherStation. The redevelopment was prompted by several factors:
- Desire to adopt a more current version of MCCI LMIC library (v3.3.0) as the original implementation had used an available, but early, snapshot of that library and its implementation for the AU915 radio environment.
- Desire to move from Arduino IDE to a more functional development environment (VSC) and associated multi-target build platform PlatformIO.
- Need to migrate the radio networking environment from TTN, The Things Network v2, to its replacement, The Things Stack - Community Edition, prior to the retirement of v2 operation in 2H21.
- Desire to move to the TTN-preferred Over-The-Air Activation OTAA of the weather station node, in place of the static Activation By Personalisation ABP that the first implementation used.
- Need to replace the humidity sensor (BME280) in the station node with a new model (SHT31-D) as it had become susceptible to condensation and thus produced erroneous readings of 100% RH for extended periods. The BME280 is a multi-sensor breakout - it was initially retained in the implementation for barometric pressure measurement - its temperature and humidity readings were no longer used. Some months further on, the BME280 failed totally, and it now has been replaced by a BMP388 for pressure measurement, prompting replacement of the sensor code library.
To ease the challenge of the LMIC library migration and to adopt a more structured approach to its process environment setup and calling, I have adopted the comprehensive example, LMIC-node, provided by Leonel Parente's https://github.com/lnlp/LMIC-node. LMIC-node provides a very complete build environment using PlatformIO, with multi-board, multi-region (i.e. radio regulation) targets. It illustrates a robust approach to developing a node that communicates via TTN. A couple of notes on the LMIC-node code inclusion in WeatherStn-2021:
- A change in the looping structure from that used by LMIC-node was necessary. The WeatherStn multi-level looping structure and reliance on interrupts with matching ISRs, was incompatible with the simpler design used in LMIC-node.
- The majority of LMIC-node code was left in place, even if not invoked in the new design, as a hedge against future changes in the environment.
- A new Board Support File for an atmMega2560 Arduino processor + Dragino Lora Shield was produced for the LMIC-node environment, to support the hardware platform retained from the original Weather Station implementation.
- While the multi-board environment of LMIC-node offered the opportunity to re-build WeatherStn-2021 for more capable hardware, e.g. Adafruit Feather M0 Lora, the original WeatherStn design relies on the TimerOne library as a fundamental software interrupt scheduler. The lack of a readily available TimerOne library for the atmelSAM environment of the Feather M0 became a roadblock, and that development path was suspended.
Minor functionality enhancements have also been added by using the javascript capabilities of Tago.IO device payload parser and its Analysis scripting:
- reject as inconsistant, an incoming data set which has been impacted by a power loss of the weather station. This condition presents as multiple zero sensor readings
- calculate an Apparent ("feels like") temperature reading from observed temperature, humidity and windspeed values
- query a backend web system from a solar PV system on-site to calculate and report a solar radiation reading for incorporation in the weather station's reporting
Note: Please refer to the above-referenced repositories of the two major code components, for details of their design, capabilities and use.
The operational dashboards of the weather station generated by this system can be viewed at either:
- TagoIO: Winston-weather, or
- Weather Underground: Winston-01