STM32f107 usb re-enumerate

Question

I have a board that is connected to USB on a STM32F107 with the following pins

USB_OTG_VBUS : PA9 USBDM : PA11 USBDP : PA12

I have a project that needs to use both Virtual Com Port and USB Mass Storage. It needs to re-enumerate the USB then do a software reset to enable the different USB class.

I have tried various different things to get it to re-enumerate but so far have been unable to, the only way to re-enumerate is to unplug usb cable.

These are some of the functions i have tried with no success

USB_OTG_DisableGlobalInt(&USB_OTG_dev);
USB_OTG_WRITE_REG32(&USB_OTG_dev.regs.GREGS->GINTSTS, 0xBFFFFFFF);
USB_OTG_CoreReset(&USB_OTG_dev);
USBD_DeInit(&USB_OTG_dev);
DCD_DevDisconnect(&USB_OTG_dev);
NVIC_SystemReset();

Would anyone have any ideas on how to get the USB to re-enumerate when it is configured with only these 3 pins for the STM32F107?

Answer 1

Before initializing USB peripheral, configure D+ pin (USBP) as GPIO output push-pull and set low (0V) for 5ms. Then initiate standard USB configuration including GPIO. After this procedure USB host recognizes new device and starts enumeration.

GPIO_InitTypeDef GPIO_InitStructure;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_ResetBits(GPIOA, GPIO_Pin_12);
delay_ms(5);

//call your USB Init here

Worked for me.

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