For the simplest of builds, 7-segment display modules usually get ... The rest of the build is pretty plain vanilla — an Arduino Nano clone, a DS3231 RTC, a Lithium battery, and some buttons ...

What do you do with 144 7-segment displays ... as [Frugha] wanted to control the clock with a single Arduino Nano. Even charlieplexing won’t get you that many I/O lines. The solution was ...