52840 usb can't be recognized

[William.wei]

Hi support team,

customer is using 52840 usb, and when they did pressure test, they find out usb can't be recognized and set address.

below is normal usb sniffer.

and below is failure sniffer

i was suppect that out D+ and D- is not responding correctly;

and after failure happens, the usb hub can't recover this 840 usb slave(reboot 840 would not solve this issue), unless reboot usb hub.

there is no clue for me to analyse this problem, please help and give some suggestion.

Regards,

William.

[Turbo J]

Why do you expect a "set address" operation in the 2nd trace?

Look closer at the "get descriptor" request: It has a valid address already, and its not for the device descriptor but for one of the strings. The host is expected to set the device address after getting the device descriptor.

[William.wei]

i mean set_address operation from host:

normally, host will set a new address to usb after 840 reset. But here, host didn't do that action, and engineer from usb hub told me that our D+ D- is not responding correctly.

normally D+ is 3.3v and D- is 0v,after we received C_PORT_RESET command from host，D+ will be 0v and D- will be 800mv as respond. 

So,may i ask where is the source code in our driver, that D+ and D- change this status,.

Regards,

William.