STM32F070F6 Bootloader USB DFU Mode not working.

[TYu.1951]

I want to use STM32F070F6 usb dfu mode to upload program. The document An2606 page 53 says:

If HSE is present and has a value of 24, 18, 16, 12, 8, 6, 4 MHz, the system clock is configured to 48 MHz with HSE as clock source. The DFU interface, USART1, USART2 and I2C1 are functional and can be used to communicate with the bootloader device.

So I use 12MHz external clock, and connect PA11/PA12 to usb, BOOT0 to HIGH. But the pc always show "Unknow USB Device".

Has anyone know how to let STM32F070F6 use USB DFU bootloader?

[TYu.1951]

Does anyone have relevant experience?

[angelos]

I suspect you have solved it by now. Your USB wiring is wrong. Either: 1) the D+ and D- are crossed or 2) you are incorrectly connecting to the ID pin of the USB connector. Because of the camera angle, I can't tell which one it is but it is definitely wrong.