These Plessey dot-matrix displays are a perfect example ... revealing that each character of the display has its own clock and data pins. The protocol is simple: pull the clock and data pins ...

For the most part, the build is what you would expect: a 16×8 LED Matrix display driven by a TLC5920 LED driver, with an Arduino that uses a DS1307 RTC (real-time clock) with a coin cell ...

The newest Echo Dot with Clock ($59.99 ... seven-segment LED display with a brighter, more functional LED dot-matrix display. Now, in addition to displaying the time, volume level, alarms ...