The CLUE screen displays the current barometric pressure as well as the last two readings, so you can see whether the pressure is rising or falling. Rising pressure will display a hot air balloon image on the screen, and sinking pressure will display a submarine.
It also shows a counter, counting up to the next reading.
The CLUE has two onboard buttons. I've used button A as an on/off switch, turning off both the NeoPixel lights and the screen. Button B turns just the screen on and off, while leaving the LED lights on.
The NeoPixels will show one of five color palettes based on the pressure reading:
- Below 960: Red
- 960-965: Yellow
- 965-970: Green
- 970-975: Blue
- Above 975: Purple
That's nice and simple, but not very meaningful. It's great to know what the air pressure is, but to predict the weather with a barometer, we need to take several readings over the course of a few hours to see whether the pressure is rising or dropping.
All you ever wanted to know about barometers and how they work, from the Art of Manliness website.
Rising pressure generally means good weather is on the way, and rapidly dropping pressure usually means a storm's a'comin'. (Your results may vary based on altitude, temperature, humidity, and whether the moon is in Aquarius -- meteorology is a complicated science).
We've put current data in the center of the piece, then as the data gets older it moves outwards towards the top and bottom edges. It's laid out like a reflected gradient, so no matter what the pressure does our artwork will look beautiful and symmetrical.
So, now that we know what we want to show and where we want to show it, we need to map out our pixel numbers so the colors correspond to the correct area on the frame.