USB Device using PA9

[Nico3]

I want to use STM32F407V in USB device MSC mode. The device has battery to run the MCU. To fetch data from device, it will be connected to LAPTOP by USB cable.

Please confirm below configuration for schematic

1) Connect PA9 to VBUS on USB connector,  perferably by voltage divider so voltage never exceed 5V. But whats the purpose of PA9 connecting to Vbus , I am not sure..

2) Do not need any pull up on USB_DP, as MCU has internal pull up as mentioned in datasheet.

I hope I am not missing any point. 

Thanks

[AScha.3]

1. >PA9 to VBUS on USB connector,  perferably by voltage divider so voltage never exceed 5V.

ok, its to detect the connection to a host : if lo , no host, if hi : now connected. (You dont need it, but you can use it.)

2. right , from rm :

You missing something for sure .... thats real life. 🙂

[STOne-32 · Accepted solution]

Dear @Nico3 ,

USB specification and in particular when going to certification process - there are some checklists operations to be fulfilled.

You can refer to this Knowledge Article for more insights 

https://community.st.com/t5/stm32-mcus/management-of-vbus-sensing-for-usb-device-design/ta-p/49485

Hope it helps You !

STOne-32