This is all accomplished with a 4×4 neopixel matrix, run by an Attiny85 Digispark with a DS3231 RTC module keeping time. A slight simplification is required to reduce the glyphs to 4×4, but we ...

An arduino based clock with 1ms accuracy over a year. Time stored in RTC continually updated by GPS module - lcsaszar/Super-Accurate-Arduino-Clock-V.KEL ...