|License||MIT-x11, Public Domain|
The CH32V003 is a 10 cent microcontroller. RV003USB is a firmware-only USB stack for the RISC-V platform.
Provided the bootloader has been installed, this allows you to flash the part without a bootloader.
As a note: Only assume that this device is as intended if the first 4 WCHARs of SERIAL are “BOOT”