weather_station/CHANGELOG.md

# Changelog

All notable changes to this project will be documented in this file.

    Added     : for new features.
    Changed   : for changes in existing functionality.
    Deprecated: for soon-to-be removed features.
    Removed   : for now removed features.
    Fixed     : for any bug fixes.
    Security  : in case of vulnerabilities.

## [0.1.0] - 2023-12-29

- First working version. But without pressure sensor. Physical RS485 bus untested, but did test ModBus over TTL serial.

## [0.2.0] - 2024-01-04

### Added

- BMP280 pressure sensor via I2C

### Fixed

- Calibrated wind vane (analog input)

### Changed

- Heater of humidiy sensor only on when humidity is above 96% (was 80%). When heater is on temperature sensor also heats up, so use temperature sensor of BMP280 when heater is on.

## [0.2.1] - 2024-01-17

### Changed

- Heater algorithm updated. Idea from datasheet of humidity sensor from Temco Controls HUM-M2 humidity sensor module.
- ModBus read register 1: Scaled wind direction by 10 in order to also get the decimal position of the direction

### Added

- ModBus read register 12: Raw rain meter
- ModBus read register 13: Temperature from pressure sensor
- ModBus read register 14: Status bits
- ModBus coil register 0 : enable/disable heather algorithm

## [0.2.2] - 2024-01-21

### Fixed

- Buffer overflow when calculating average wind speed in AverageOfArray(). Fix: use 32 bit register for average_value.

### Changed

- Changed some variables to the propper standard (uint8_t, uint16_t, etc.)
- SparkFun wind interrupt now calculates over 3 seconds in stead of 1 second (KNMI standard)]

## [0.2.3] - 2024-02-28

### Changed

- Humidity often got stuck at 100%. Heater algorithm now heats for 10 minutes and cools down for 10 minutes (was 5min/15min)

## [0.2.4] - 2024-03-08

### Changed

- Humidity timer back to 5/15 minutes: shorter cooling times give false temperature readings.

### Fixed

- Classic 0/1 error in max and average calculating routine, which resulted in a buffer overflow.

## [0.2.5] - 2024-03-11

### Fixed

- 0/1 error in max and average (again, or better said: still!).

### Changed

- Humidity threshold heater is now a define instead of hard coded numbers in the source.

## [0.2.6] - 2024-03-13

### Fixed

There is a bug in the Si7021 chip: when the sensor is exposed to extreme environmental conditions for a longer period (very high or very low humidity), the humidity register will wrap around and give wrong values. (https://community.silabs.com/s/question/0D51M00007xeOo9SAE/si7021-relative-humidity-reading-underflowing-?language=en_US).
Workaround: let's assume the humidity will never go below 15%. In the Netherlands a humidity below 20% is rare, but can occur and the minimum value ever measured in De Bilt was 6% (on 1 april 1965). At several other sites in the Netherlands the humidity went as low as 10%. But as this was a one time event and the measurements are doubtful, this event was not registered in the original database. (https://nl.wikipedia.org/wiki/Relatieve_luchtvochtigheid)
In rare cases, the humidity value could creep up above 15% (when the actual humidity is 100%) and still give wrong values.

## [0.3.0] - 2024-05-02

### Added

Support for HYT-221 humidity sensor

### Removed

Support for si7021 humidity sensor (this sensor was not suited for outdoor measurments)