I'm using the Teensy 3.1 has a built in clock if you solder in a 32kHz crystal. However, that's an expensive part to have lying around in a clock. If I had had a ATMega328 lying around, I might have used that instead, but I needed something quick.
This was also my first attempt at making a double sided PCB and using strands of twisted core wire to connect the top and bottom (the poor man's through-hole plating.) There were a few errors on the PCB - one because I moved the layout and forgot to move a trace, and another because my laser printer isn't that good. Fixed by drilling a few holes under the LED Matrices to cut some traces and attaching things with some wires...
Still to do:
- Flashing colon to separate hours and minutes
- Add buttons to change/set time and show/set date
- Maybe a rotary encoder to change the time
- Create the PCB for the rest of the project