Here’s a super-nerdy timepiece created using Arduino, a DS1307 real-time clock chip, four 74HC595 shift registers, and an 8×8 RGB dot matrix display. How does it tell time?
The time is indicated using blocks of colour. The central 6×6 grid is split into 4 x (3×3) grids and each 3×3 block is a different colour. The number of LEDs per 3×3 grid indicate the digit. i.e. if the first 3×3 grid has 1 LED lit then the first digit is 1, the second has 7 then the 2nd digit is 7, etc. The top two grids are the hour digits and the bottom 2 the minutes. Around the edge the unused LED’s have a moving light that shows the approximate position of the seconds.