This is a somewhat silly project to make a digital clock that displays the current time (hour and minute) in hexadecimal.
Here is a picture of the prototype (click to embiggen):
The KiCad schematic for the prototype circuit is in the hw_proto directory. The required parts are:
- Arduino Nano
- DS1307 i2c real time clock chip
- 4 common anode 7 segment displays
- 4 2N3906 PNP transistors (to switch common anode voltages for LED displays)
- 4 4.7k Ohm resistors (to drive gates of the PNP transistors)
- 2 1K pull-up resistors for i2c SDA and SCL lines
- 7 current limiting resistors for segment cathodes (I used 220 Ohm)
- 3 normally open pushbutton switches
- 5V power supply of some kind
The software is in the HexClock directory. It requires the RTCLib and Bounce2 libraries, both of which you can install using the Arduino package manager.