Does Dfu capability on a device depend on firmware running on this device?

[FLett]

I haven't found Dfu code anywhere.

[Tesla DeLorean]

What device, try to be specific

STM32Cube_FW_F4_V1.21.0\Projects\STM32F446ZE-Nucleo\Applications\USB_Device\DFU_Standalone

Some devices support DFU in ROM, review the documentation AN2606

https://www.st.com/content/ccc/resource/technical/document/application_note/b9/9b/16/3a/12/1e/40/0c/CD00167594.pdf/files/CD00167594.pdf/jcr:content/translations/en.CD00167594.pdf

[FLett]

Thanks for your answer! Since yesterday I read some more internet stuff and read that either external flash or device flash may contain the Dfu code. I just got AN2606, perfect. Now I need to figure out why my, probably factory programmed, Dfu code doesn't do anything.