Requirements

• Arduino SW with stm32duino addon (module has bootloader)
• Installed SlowSoftWire
• USB cable which can be cut for connecting module to computer

Instalation of Arduino and support for stm32 (stm32duino)

• install Arduino ide + stm32 support following this how-to

• download and install SlowSoftWire, here is howto do it

• create directory audi_volume_fix_stm32

• download two file from here save link on your computer as audi_volume_fix_stm32.ino in directory audi_volume_fix_stm32 and here save as audi_concert_panel.h in directory audi_volume_fix_stm32

• open audi_volume_fix_stm32.ino with arduino

• then select stm32 generic mcu: menu Tools -> Board: "XXXXXX" -> under STM32F1 Boards (Arduino_STM32) select Generic STM32F103C series"

• try compile downloaded software, hit left icon or in menu select Sketch -> Verify/Compile or use Ctrl+R. After successful compile arduino will write simple "Done compiling." and in lower status window will be no error messages, just white text, no orange text.

Connecting to computer

Then you need connect module to computer USB port, module has 4pin terminal marked USB:

Unfortunetlly D+ and D- are swapped so direct connection of female USB-A connector is not posible.

You can solder USB cable directly to module, or use long dupont male terminal for temporary connection:

Uploading new firmware

Connect module to computer (module can stay in radio, just disconnect radio from car wiring)

New device (serial port) should be created on computer, select this port for upload in arduino menu Tools -> Port -> *DEVICE* (Maple Mini)

Then hit upload, second icon in menu or Sketch -> Upload or use Ctrl+U

After successful upload, you can disconnect module and test it out.

If you like to revert to previous version download this source code and use same procedure.