STM32F303xB: How to reset USB Endpoint on USB disconnect ?

[Prasant J]

Posted on August 18, 2017 at 08:34

Hi,

I'm using custom hardware that has STM32F303VB (firmware version F3 v1.8.0) and uses USB in self-powered mode.

I have modified USB Custom HID class to appear as USB Vendor Class (1 IN + 1 OUT endpoint). USB Vendor class is working fine except one generic case. The USB communication does not work after the USB cable is disconnected and reconnected.

I'm assuming the problem is that the endpoints are not reset when the cable is disconnected. I did not see such a function in the USB HAL.

Has anyone implemented endpoint reset functions?

Did anybody face a similar problem?

Any inputs will be of help!

Regards, Pj

#stm32f303 #usb #endpoints

[Ben K]

Posted on August 18, 2017 at 19:06

I would recommend checking the following steps during USB reconnection:

1. Reset signal is sent from the host, check that your code closes all non-control endpoints (EP > 0) from USBD class DeInit callback
2. Device setup by the host (setting bus address, reading descriptors), check that the device is recognized at all by the PC
3. The host selects the USB configuration (typically only one configuration is available), check that your non-control endpoints are opened from USBD class Init callback
4. Class-specific USB configuration by the host
5. Communication through the non-control endpoints

If we know which step fails it is much easier to tell what exactly went wrong.

[Prasant J]

Posted on August 21, 2017 at 15:20

Hi

Kupper.Benedek

‌,

Thanks a lot for inputs!

I traced the steps mentioned by you.

1 to 3 work.

Step 4: Since its vendor class there is no class specific initialization.

Step 5:fails.

Any further checks that you think I should do?

Regards, Pj

[Ben K]

Posted on August 21, 2017 at 21:01

In this case I wouldn't blame the device, but would rather investigate the device driver on the host (PC) side. Does it have a custom driver, or uses a built-in mouse/keyboard driver? I haven't worked with HID myself yet, but it is possible that the driver is not detecting the detachment of the device, and thus keeps communicating on the broken channel instead of re-initializing it.

This is as much as I can add to this topic, I hope you manage to solve the issue (keep us updated).

[Prasant J]

Posted on August 22, 2017 at 14:42

Hi

Kupper.Benedek

‌,

Thanks for inputs. I found the problem.

It was in the device and nothing to do with the HAL.

Bad coordination between my user state machine and USB HAL (bad design from my end).

Your input (Point No. 1 - USB Reset from Host) helped me solve the problem.

We do not have USB VBus connected to the Device.As a work around we use Suspend/Resume to checkUsb Cable disconnection &re-connection (not the right way but works for our cases).On USB cable re-connection, my user state machine was getting the Resume callback from USB HAL before the USB HAL was reset & initialized. So my user state machine would setup endpoints with buffers and after that USB HAL would be reset and waiting for user state machine to act on it.

So the user state machine is waiting for data callbacks from HAL while HAL is waiting for buffers from user.

I have fixed this now.

Thanks again for your inputs.

Regards, Pj

[Andrew Sund]

Posted on October 11, 2017 at 19:29

Thanks! You identified exactly what I have to do for my project.

[mohan raj]

Posted on July 12, 2018 at 09:07

Hi,

I am using STM32F103VCT6 for my project and I have Polling the data packets from Uc for every 200 milliseconds and send to PC,Sometimes USB Communication is disconnected.

when I debugging and find that Transmit state is set to one.afterwards USB port is disconnected,is any solution to reconnect the USB port when the port is in disconnected state.

uint8_t CDC_Transmit_FS(uint8_t* Buf, uint16_t Len)

{ uint8_t result = USBD_OK;

/* USER CODE BEGIN 7 */

USBD_CDC_HandleTypeDef *hcdc = (USBD_CDC_HandleTypeDef*)hUsbDeviceFS.pClassData;

if (hcdc->TxState != 0){ -------> always Set to One. return USBD_BUSY; }

USBD_CDC_SetTxBuffer(&hUsbDeviceFS, Buf, Len);

result = USBD_CDC_TransmitPacket(&hUsbDeviceFS);

/* USER CODE END 7 */

return result;}