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USB (HID_STANDALONE demo on STM32H7B3) - How is URB Functions set?

BBrow.2
Associate III

I cannot figure out how the USB sets the Function selector output.

URB Function: URB_FUNCTION_GET_DESCRIPTOR_FROM_DEVICE (0x000b)

 

URB Function: URB_FUNCTION_SELECT_CONFIGURATION (0x0000)

 

URB Function: URB_FUNCTION_SELECT_INTERFACE (0x0001)

I can modify bRequestType and bRequest, but that does not affect the URB Function selected just after the IRP ID and IRP USBD_STATS info.

eg. Wireshark Dump:-

Wiredump1.jpg

0b 00 is URB Function: URB_FUNCTION_GET_DESCRIPTOR_FROM_DEVICE (0x000b)

When I select configuration, the 0b 00 becomes 00 00, but how?  I cannot find any place in the firmware or hardware, that relates to this?

Am I making sense?

 

2 REPLIES 2
BBrow.2
Associate III

Beginning at 80 06 05 03 above is the FIFO out, so where does the preceeding bytes come from?

BBrow.2
Associate III

I am thinking that winpcap creates this term and number (URB_FUNCTION_GET_DESCRIPTOR_FROM_DEVICE (0x000b)) and that it is not an actual number directly sent over USB?