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2021.5 internal weather forecasting

The last few weeks have been getting pretty sweaty in the house.

With all of us doing rides on Zwift for Tour de Zwift, me doing the “back to fitness” training program and the fact that the bike is setup in the kitchen area means that the humidity had been climbing even with having windows open!

This raised the question of “how humid”? with a further question of can I measure it and then use that info to deal with it.

Luckily I already had a clever little bit of kit called a weather:bit (https://coolcomponents.co.uk/products/weather-bit) This is an extra sensor board that plugs into a BBC micro:bit.

I originally brought it for an old code club where we were going to make a “it’s likely to snow” detector! Using maths from here: http://www.sciencebits.com/SnowAboveFreezing

The micro bit (https://microbit.org/) is an amazing piece of tech, really good for teaching kids about programming and hardware. Also only around £10!

Using the code blocks programming system (https://makecode.microbit.org/) it took all of 5 minutes to setup something to measure and display the humidity every 5 seconds on the display.


Micro:bit with weather:bit showing humidity every 5 seconds

Ok, now we needed to understand what’s “normal” and what’s “OMG OPEN A WINDOW!”

Leaving it for a day or so it settled down to about 50-55.

Next day was a TDZ stage where I managed to get it to register 72!!

Now that the limits were known, we just had to figure out what to do about it. The obvious choice is a dehumidifier, but they aren’t normally internet connected/controllable.

No matter, I have a spare TP link WiFi plug and they have a Python API that saves me writing my own: https://pypi.org/project/tplink-cloud-api/

Python is handy as the micro:bit can run Python too! https://microbit.org/get-started/user-guide/python/

But sadly that’s where this story ends, as the dehumidifier that we brought (https://www.diy.com/departments/dimplex-everdri10e-10l-domestic-use-dehumidifier/5011139071125_BQ.prd ) actually has a ” start/stop at this humidity” function :-(

Oh well, I’m sure I can think of something else to automate :-\