I've purchased the following board: http://www.ebay.com/itm/STM32F407VET6-Mini-version-core-board-STM32-minimum-system-version-/291791335845
and having issues getting USB working. Looking at the STM32F40x STM32 manual:
There should not be any resistors on USB lines because the OTG USB Phy does this according to the manual. The board has a Pull up on DM (PA12) and 22R on PA11 and PA12. I don't think 22R should matter but, pull up on DM will.
Any suggestions? (I'm thinking of removing the resistor see if this makes it work)
-Found the issue, If VUSB is not connected DM needs a pull up
- STM32 code needs to be edited to disable VUSB sense.
HAL_StatusTypeDef USB_DevInit (USB_OTG_GlobalTypeDef *USBx, USB_OTG_CfgTypeDef cfg)
// FIX USBx->GCCFG |= USB_OTG_GCCFG_VBUSBSEN;