Over the past few months, I digged more deeply into the Arduino platform. One ongoing project is a clock with moon phase display (since I already implemented the computations for my astronomy app, Cor Leonis). I started out with an LED matrix and 7-segment displays like this:

Tons of wire!

Over time, I decided to use 2 8×8 LED matrices, switched to a smaller Arduino compatible board (Adafruit Pro Trinket), and ran it on batteries:

There’s also a button to switch between views now.

It’s far from done, but I find it amazing how much I already learned from this relatively simple project… a refresher on basic electronics (resistors, capacitors, etc.) and soldering,  manual LED matrix display multiplexing, more on LEDs than I ever wanted to know, RTC clock chips, LED display driver chips, shift registers, step-up/down voltage converters, debouncing HW buttons, I2C bus wiring and communications, calculating power consumption and battery lifetime, and so on and so forth. Next up is sensors: I would like to switch views just by waving my hand (and see how robust that is), instead of having to walk over and press a button.