Re: [usb] usb clarifications

["Vikas T Rao " <vikasraot@myw.ltindia.com>]

** Proprietary **

hi ravi,

hub should recognise the device attachment and detachment. this will be indicated to the host by the status change endpoint mechanism if it is a hub, if hub acts as root hub then it will be reported in the port control and status register. i suggest you to go through the chapter-->11 refer 11.12 hub controller.

...vikas


>>> ravikumar_vlsi@yahoo.co.in 06/17/02 09:45PM >>>
hi all,
I understand that usb host polls devices in frequent
intervals for periodic kind of transfers (namely
Isochronous & Interupt Transfer type) , but with what
frequency that it polls the Hub's Status endpoint  for
detecting the attachment & Detachement of usb devices.

I beleive the frequency that it polls the Hubs status 
Descriptor is relatively higher -- Would u pls clarify
whether i have understood correctly 

Regards
Ravikumar





 --- senthil  nadesan <senthilnadesan@rediffmail.com>
wrote: > 
> Hello ravi,
>   Gothrough the lines within codes,it is taken from
> the usb 
> specification 1.1 in the page 231.
> 
>          "In the downstream direction, hubs operate
> in a broadcast 
> mode. When a hub detects an SOP on its
> upstream port, it establishes connectivity to all
> enabled 
> downstream ports. If a port is not enabled, it does
> not propagate packet signaling downstream."
> 
> With regards
> Senthil
> 
> 
> On Fri, 14 Jun 2002 Ravi Kumar wrote :
> >hi all,
> >In USB .
> >Consider the OUT transaction ,
> >will the host controller
> >sends the data to all the devices in broadcast or
> >will it  select particular hub where the devices is
> >anchored & send the data to that particular hub .
> >
> >Pls reply
> >Regards
> >Ravikumar
> >
> >
> >
> >
> >  --- govindsrajan@hotmail.com wrote: > Hi,
> > >
> > >    During an enumeration process, what should be
> the
> > > address value in
> > >    the Setup Token. Is it always "zero" or the
> > > address value of the device
> > >    which is being sent in "Set Address" command
> in
> > > the data phase?
> > >
> > >    SetUp Token (Sync,Pid,Addr,Endp,crc5,Eop) ;
> Addr
> > > = 0 /  [1-128] ?
> > >    Data            (Sync,Pid,Data0,crc16,Eop); 
> //
> > > Data0 has the command
> > >
> > >    If I change the address of a device, what is
> the
> > > address value in the
> > >    Setup Token. Is it zero or the old value?
> > >
> > >    A quick reply is appreciated.
> > >
> > >    Thanks
> > >    Govind
> > > --
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