weather_station/README.md

# Weather station with ModBus over RS-485

## Abstract

A weather station build around a SparkFun Weather Meter Kit (SEN-15901). The temperature, humidity, ambient lightmeter and pressure are measured with I2C sensors housed in an RS1 Passive Radiation Shield from Garni. The data is available via an RS485 ModBus RTU interface. The main processor is an Arduino Pro Mini (ATmega328P 5V@16MHz)

![Block diagram of weather station](./build-doc/images/block_diagram.svg "Block diagram of weather station")

## Documentation

An apprehensive description of the project can be found here: [https://meezenest.nl/mees/weather_station.html](https://meezenest.nl/mees/weather_station.html)
## Sensors

- SparkFun SEN-15901 Weather Station (wind speed, wind direction and rain fall)
- Innovative Sensor Technology IST AG HYT 221 (humidity and temperature)
- Bosch BMP280 (pressure)
- DFRobot SEN0562 (ambient light)

## Measurements

- Wind direction
- Wind speed (average of last 10 minutes)
- Wind gust (last 10 minutes)
- Rain fall (last hour)
- Rain fall (last 24 hours)
- Temperature
- Humidity
- Atmospheric pressure
- Ambient light

## ModBus

- RS485 transceiver
- ModBus address: 14 (fixed in software)

## Dependencies

- Arduino IDE

### Arduino libraries

- https://github.com/sparkfun/SparkFun_Weather_Meter_Kit_Arduino_Library
- https://github.com/orgua/iLib
- https://github.com/epsilonrt/modbus-arduino
- https://github.com/epsilonrt/modbus-serial

Libraries are included with the source code of this project

## Known issues

- Pressure sensor (BMP280) failed after one year outside. Probably due to the long period of fog we had in the winter.
- Rain fall meter is sensitive for mechanical shock. Mount it on a sturdy pole to prevent false readings.

## License

Copyright (C) 2023-2025  M.T. Konstapel

### Software

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

### Hardware and documentation

This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.