This was a demo for my VGA library.The demo clock simply "draws" a flipped digital clock with randomly generated text inside a buffer while the VGA library handles all the timing and character generation for a VGA.
The RTC update is done via a call back in the vertical refresh using a NCO (Numerically-controlled oscillator) algorithm for the 1Hz update instead of the STM32F030 RTC peripheral in the STM32F030 because I haven't written the code for it until my Audio switching project a year later.
The bare minimal schematic (youtube video)
A 25MHz oscillator was used during the prototype stage on a breadboard.
The final ChibiTerm unpopulated PCB is available on OSH Park.