|
Message
From: M. AbuKhater<perocletos@y...>
Date: Mon Apr 12 16:15:28 CEST 2004
Subject: [usb] 2.0 Hub
hi
"A high speed hub makes the speed conversion from high to full/low speed for the full/low speed device. "
Well, since the hub broadcasts, I don't think it can do speed conversion for all packets (USB2.0 is 40 times faster than 1.1), so how does it know that a certain packet is directed to this Full-speed device?
Does the hub keeps the address and speed of each device connected to it as a database inside it? if so why does it broadcast ?
Abukhater
Marc Reinig <mreinig@p...> wrote:
Actually I dashed that off too quick.
High speed traffic is broadcast to all downstream high speed devices. If there is a low or full speed device down stream of a high speed hub, it will be attached as a low or full speed device either directly to a high speed port, or through a full speed hub, which will be connected as a full speed device. A high speed hub makes the speed conversion from high to full/low speed for the full/low speed device. It effectively acts like a host controller in this case. See 11.14 in the USB spec.
Marc Reinig
System Solutions
-----Original Message-----
From: usb-bounces@o... [mailto:usb-bounces@o...]On Behalf Of Marc Reinig
Sent: Sunday, April 11, 2004 7:46 PM
To: Discussion list about free,open source USB IP core
Subject: RE: [usb] 2.0 Hub
-----Original Message-----
From: usb-bounces@o... [mailto:usb-bounces@o...]On Behalf Of M. AbuKhater
Sent: Sunday, April 11, 2004 2:09 PM
To: usb@o...
Subject: [usb] 2.0 Hub
happy easter all;
lets say a USB2.0 hub is connected to a host , with many high-, full- and low-speed devices connected to it.
> as indicated in the USB system architecture , a full speed packet
> is heared only by full speed devices , same for low- high-speed devices.
> does this mean that the host sends low and full speed frames to high speed hub?
No, a high speed host communicates with a high speed device at high speed. The hub is a high speed device.
> if not how does the hub knows which packet is should go to which device?
Uh. The device address?
Marc Reinig
System Solutions
_______________________________________________
attachment.htm
|
 |
Browse
