Its been a while since I wrote anything here, but today’s post is how to run a common cathode multi digit seven segment display without extra shift regs or buffers.
I software multiplex the segments and use the INPUT_PULLUP mode of the digital pins to ensure only one digit is written to at a time.
I have actually used an RTC module for the time, but you don’t need one if you keep the power on and add a bit of setting logic :)
All the docs are in the code.