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

In version 1.4 you can use clock verticaly and show some short messages (you can use two inputs). If you connect input 10 and/or 11 to GND you can show one of them. You can upgrade text of message only in code, see row around 420 (look for '//show some message or time'). More information in code.

Menu:

• H: Hour

• M: Minute

• y: year

• m: month

• d: day

• /: 12/24h time format (00 = 12h time format, 01 = 24h time format)

• f: Font (show # of font in select font style 01 - 05)

• :: Dot style (0 - hide, 1 - show, 2 - blinking)

• b: Backlight intensity (00 - 15)

• D: Show date (what second is date shown; 00 = newer, 60 = always)

• t: Show temperature (what second is temperature shown 00 = newer, 60 = always)

• R: Font turning 1 (turn each character; 00 = off, 01 = on)

• r: Font turning 2 (turn all diplay; 00 = off, 01 = on)

• U: Turn font UpsideDown (00 = off, 01 = on)

• v: Vertical mode (00 - standard horizontal, 01 - vertical mode)

• Strt: Reset second (set to 0) after release the button and show actual time

You need:

• 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/arduino-hodiny-s-maticovym-displejem/ You can use forum there.

See video: https://youtu.be/HDweqN9cDNA