I was in Rockville the other day and stopped by the Micro Center. I found a neat gadget in the back:
https://shop.pimoroni.com/products/unicorn-hat
I decided to make a digital hourglass using it. Starting at midnight it does the following:
- Around every 30 seconds, a grain of sand is randomly dropped into the matrix.
- At 30 minutes, the the matrix is full and then grains of sand randomly drain out.
- At the hour, the matrix is empty and a blue hour marker is added
- Every five hours a red hour marker is added instead and it erases the previous blue markers.