Greetings from a new RuuviTag user. I noticed that all my four RuuviTags (using latest firmware v3.31.1) react quite slowly to humidity changes, compared to my two cheap digital humidity meters I bought from Clas Ohlson. For example, when I open balcony door, or turn on the shower, my cheap meters react almost instantly (3-5 minutes), but for RuuviTag it takes about 30 minutes to reach new min/max level.
I assume some kind of filtering / averaging of the humidity values is used, to reduce the noise. What kind of filter is used, if any? Where can I find this filtering in firmware source codes?
The slowness is mainly caused by the gore-tex sticker in RuuviTag enclosure, it has some delay in letting moisture through. RuuviTags up to hardware variant B6 have enabled internal low-pass filtering of BME280 sensor, tags made in last 2 years or so have SHTC3 sensor which does not have such a filter.
You can remove Goretex-membrane when you are using sensors indoors and place the round hole on top of the sensor (~3mm left from the golden battery connector). This will speed up the changes.
Thanks for your responses. So, basically, there is a Goretex sticker -based “mechanical filter” in RuuviTag. The slowness is not a problem for me, I was just curious. Actually it is a good thing, since it filters out some measurement noise, although I don’t know how noisy the sensor values are without any kind of filtering. And because of this “filtering”, I can use smaller hysteresis if I want to control my Ufox humidifiers with RuuviTag and smart power outlets.
BTW, does the alignment of the hole in relation to sensor matter, when the Goretex-membrane is used? And when the products are shipped, is the hole always aligned with the sensor?
Based on the tests it’s a bit faster if you align to the top of sensor (black sensor with hole in the middle, located ~3mm clockwise from the golden battery clip).