Projects

Andy

Monitoring My Indoor Air Quality

In my last post I mentioned that I also wanted my info display to show the current indoor temperature, read from the air quality monitor that I made. I built the air quality monitor a couple of years ago – it was my first experience playing with an Arduino and was a lot of fun (interspersed with moments of utterly frustrating confusion). I thought I’d put together a quick intro to what it does and how I made it.

Why Build An Air Quality Monitor?

I saw an advert for an attractive little box that you put on a shelf that monitors the air quality in your room. It has an app to view the data and send you push notifications if it the air was too unhealthy. I loved the idea – I’m a big tracker of data (I once had to log of every single ingredient of every single product I ate for an entire year) and thought it would be really interesting to find out what my environment in my house is like.

I considered buying it… I really did. Then I decided I could totally build my own. I started by buying some sensors:

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Andy

Building an eInk Info Display For My Living Room

Like a lot of Londoners, my trip to and from work involves moving between a few different trains, any of which could be delayed and cause me to be late to work. Or worse – late home. As checked the tube status on my phone over breakfast one morning, I realised that it would be super useful to have some kind of display in my living room allowing me to see at a glance how my commute is looking before I set off, so I can go a different way if needed.

There are a few options to create a display like this – I could re-purpose a tablet or phone in the technology graveyard drawer, writing a quick and dirty app to run on it. But where would the fun in that be? Sure, it would work but I wanted to learn something along the way. I decided to use a Raspberry Pi and a display of some kind, but if its going to live in my house, it needs to be pretty.

I ordered the Primoroni Inky wHAT – an eInk display with all the headers to screw it directly onto a Raspberry PI. It even has Python library for displaying stuff. I went for the two-colour red/black model; I thought I could use the red mode to make any tube status issues stand out.

Features

As soon as I’d ordered the screen, I started thinking about what I would use it for. I came up with a few things I wanted to do:

  • Display the current tube status of the most useful tube lines
  • Display the current weather / temperature outside from DarkSky
  • Show the current indoor temperature, pulled from my Air Quality Monitor (I built this a couple of years back, I might cover it in a later post)
  • Display some kind of indication that central heating is on or off
  • Show the time

I drew this little diagram to get started:

Implementation

APIs

Ever the software engineering project, the first task was to investigate the APIs to give me the data I wanted.

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