Re: USB Bus Reset - General Query on USB

On Thu, 29 Oct 2009 06:21:52 -0500, Sandeeptssmg wrote:

> Hi All,
> my first query on this excellent site :-). Am currently looking for some
> info on USB reset. In a USB enumeration failure scenario, could you please
> let me know how many times does the hub driver sends a RESET to the device
> before it recognizes that USB cannot be enumerated and pops up a msg "USB
> device unrecognized".
>
> I presume its 3 times before the host driver can pop the error msg on the
> screen. Does it vary based on different host controllers or is it a
> standard ? Please provide if any pointers ?

The host must retire a transfer after 3 errors, according to the
2.0 standard. See section 10.2.6. It doesn't say anything about sending
another RESET.

http://www.usb.org/developers/docs/