Simple Arduino Clock with LED matrix display 32 x 8 pix. In this sketch is LedControl library (https://github.com/wayoda/LedControl) used.

• Arduino Nano
• DS3231 module
• 4x LED matrix with MAX7219 driver (used LedControl library)
• 2x button

For use external power supply (no USB) you need

• 1N4148 diode
• 5V power supply

More info in Czech language: https://www.mylms.cz/text-arduino-hodiny-s-maticovym-displejem/

See video: https://www.youtube.com/watch?v=HScHKPGg8lE