USB XACT_ERROR response on BulkIn request

[SteMMo]

Hi all,

we are developing a board based on STM32F429 chip.

In particular I'm developing a composite USB device on USB OTG port, showing a custom device + a CDC device [ep 0x85, 0x06, 0x83] using USB_Device_Library code.

Windows correctly shows 3 items: a composite device, a generic USB device with my custom label/name, a virtual serial port (COM8).

When I try to open the virtual port (by Putty) I see nothing on the terminal but if I inspect with Wireshark I see an infinite loop of BulkIN request, BulkIn response with XACT_ERROR, a RESET_PIPE_AND_CLEAR_STALL with both request end reply.

I'n wondering why I have the XACT_ERROR on BulkIn request: I'm not able to find the point. I break-pointed some code in the HAL_PCD_IRQHandler() routine but it's hard to step in an interrupt handler.

Very similar code (but compiled for STM32MP135 demo board) is working correctly.

I'm focusing on USB_OTG_GINTSTS_IEPINT interrupt but which is the routine that replies to BulkIn?

Maybe the PCD_WriteEmptyTxFifo() ??

Thanks

[SteMMo]

Adding some notes...

Comparing with the run on the DEMO board I noticed that the IRQ handler is never recall  with interrupts for EP IN 5 (0x85), only for EP 0.

I guess that the XACT_ERROR is caused from the missing reply.

On the DEMO board the EP IN is 0x82: in a simple log the opening of the serial port is:

IRQ IEPINT - ep_intr: x4
- epint ep.2 x1
- IEPINT XFRC ep.2

IRQ RXFLVL

IRQ IEPINT - ep_intr: x4
- epint ep.2 x80
- IEPINT TXFE ep.2
WriteEmptyTxFifo ep.2

From the Wireshark capture I see the BulkIN packet toward 0x85 IN endpoint !

How it is possible?

[SteMMo]

From the reference manual, it seems that EPs greater than 3 are not supported for FS USB mode, so it is impossible to set the mask for EP 5.

Please, can anyone confirm this?