Firmware is a MounRiver Studio project. You can freely download MounRiver Studio at http://mounriver.com/download
## Flashing
Firmware can be debugged and flashed from within MounRiver Studio using a WCH-LinkE debug probe.
Alternatively, a UART bootloader is available. A Windows flashing utility is provided. The bootloader uses WCHISP protocol, so any WCHISP flash utility supporting CH32V003 should work (untested).
Connect any standard TTL UART into the GAT header in the rear, power with 3V3, then use the flashing utility to load new firmware.
To activate the bootloader, hold down BTN2 while powering on. LED4 (orange) will rapidly flash to indicate the addon is in bootloader mode.