CH32v3xx internal usb bootloader

That's a topic, i've been playing with recently. The CH32V3xx and CH32V2xx RISC-V families have a internal bootloader than is able to flash software over USB or UART.No need for swindle, wch-link, ... (you'll need them to debug though).You can use that to flash the CH32V3xx DFU bootloader for example.There is a very nice project CHISP-Flasher that can flash elf/bin/.. over USB and available both as CLI or with a Qt6 GUI.Warning: not only do you need to have the BOOT0 pin High at boot, but you ALSO need to have the PB2 pin grounded at boot.