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USB 2.0 D+ PullUp requiered?

Question asked by brammer.benjamin on Mar 18, 2017
Latest reply on Mar 20, 2017 by brammer.benjamin

Hi Guys,

I want to implement the STM32F303VET6 for possible DFU or CDC / HID . I am a little bit mixed up with the schematics of the USB ST-LINK for USB interfacing. Is the 1,5k PullUp on D+ mandatory? And if it is, do i need to implement the possibility to activate or deactivate it? the schematics from the ST-LINK use a GPIO for that purpose but where in the middlewre software do I need to implement that PullUp switching?

When I use the STM32CubeMX software and want to activate the USB only both differential lines are set but no aditional GPIO port for the PullUp. On the other hand the datasheet recommends to use the PullUp since it is requested in the USB 2.0 spec. So if the PullUp is a must, why is there no true description on how to implement that PullUp right in software and layout?


best regards