v2
==

same USB type-A plug form factor.
change MCU to STM32F042 since it provides read out protection, can recover 48 MHz clock from USB, and is easy to solder.

v1
==

smaller form factor.
fits in USB type-A port.
uses CH32V203 as it is smaller, cheaper, and requires less external parts (DP pull-up, crystal).

issues:

- USB pins are mirrored

v0
==

this is a large development board.
it accepts the classical STM32F103 (which I'm more familiar with), and CH32V203 (cheaper).
it has a proper debug port and buttons.

issues:

- USB pins are mirrored