Here's an unused schematic I built in Altium Designer that I did for SJSUs formula racing team. The idea was to modify the existing STM32 blue pill circuit to add CAN and VFD interfacing functionality. The purpose of building this circuit ourselves was so that we could have a PCB without having to stick an already built STM32 blue pill on to it. This way we could customize the layout ourselves and would've led to a slimmer profile as we wouldn't have the thickness of our PCB in addition to the STM32 blue pill on top. This schematic helped me and my team at the time learn how to interface with the STM32F103C8T6 MCU at the heart of this circuit and what's required to take advantage of the various functionalities it can offer.