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Driven SE 0
by Virendra on Nov 29, 2004 |
Virendra
Posts: 7 Joined: Aug 4, 2008 Last seen: Feb 25, 2011 |
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I would like to know as to how does the USB host drive SE 0 on the bus. I mean the exact events those happen during driven SE 0. I also want to know as to how the UTMI responds to generate SE 0 on its LineState signal.
Regards,
Virendra.
Yahoo! India Matrimony: Find your partner online.
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Driven SE 0
by Unknown on Nov 29, 2004 |
Not available! | ||
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Hi Virendra,
The picture that i see as a USB host is HOST --> PHY ---> USB BUS. In this case if the PHY is UTMI, the host has to just keep it in high speed mode with a proper combination of xcvr_select and termselect signal. I actually dont remember, but from what i remember both should be tied to ground.(just incase check with UTMI spec). When the host ties both those signal to ground, the PHY just activates its pulldown resistors( 15k to both D+ and D-) thereby bringing down the USB bus to SE0 state. On seeing xcvr select and termselect activating high speed, the default state of the USB bus for high speed is SE0, therefore the transceiver reflects this default state in the line state. I hope this clarifies your query. Regards, Ravi Rajaraman
From: Virendra virendradhavale@yahoo.com>
Reply-To: virendradhavale@yahoo.com, "Discussion list about free,open
source USB IP core" usb@opencores.org>
To: usb opencores usb@opencores.org>
Subject: [usb] Driven SE 0
Date: Mon, 29 Nov 2004 09:42:37 +0000 (GMT)
I would like to know as to how does the USB host drive SE 0 on the bus. I
mean the exact events those happen during driven SE 0. I also want to know
as to how the UTMI responds to generate SE 0 on its LineState signal.
Regards,
Virendra.
Yahoo! India Matrimony: Find your partner online.
_______________________________________________
http://www.opencores.org/mailman/listinfo/usb
_________________________________________________________________
Hey there NRIs! Desi news, films, ‘n more! http://www.msn.co.in/nri/ Stay in
the loop!
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Driven SE 0
by Unknown on Nov 29, 2004 |
Not available! | ||
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Hi,
The HS transceiver has 45 Ohm Rs (series resistance) and 15KOhm Rpd (pull down resistance). The Rs resistance is connected at the output of the FS/LS driver of the HS xcvr. This Rs resistance is connected both at the downstream and upstream port. So in combination they provide a 90 Ohm impedance match to the USB cable. To signal SE0, a strong one, the downstream port's FS/LS driver drives current through the 45 Ohm Rs. The Rpd resistances can give only a soft SE0. For details refer to the Fig 7.1 of USB2.0 specs. As far as I know the UTMI is only used for the peripheral i.e. on the upstream ports. So the question of driving SE0 doesn't arise. Anyway Linestate[1:0] is an input to the SIE and cannot be driven. Regards, Neelabh Ravi Rajaraman wrote:
Hi Virendra,
The picture that i see as a USB host is HOST --> PHY ---> USB BUS. In this case if the PHY is UTMI, the host has to just keep it in high speed mode with a proper combination of xcvr_select and termselect signal. I actually dont remember, but from what i remember both should be tied to ground.(just incase check with UTMI spec). When the host ties both those signal to ground, the PHY just activates its pulldown resistors( 15k to both D+ and D-) thereby bringing down the USB bus to SE0 state. On seeing xcvr select and termselect activating high speed, the default state of the USB bus for high speed is SE0, therefore the transceiver reflects this default state in the line state. I hope this clarifies your query. Regards, Ravi Rajaraman
From: Virendra virendradhavale@yahoo.com>
Reply-To: virendradhavale@yahoo.com, "Discussion list about free,open
source USB IP core" usb@opencores.org>
To: usb opencores usb@opencores.org>
Subject: [usb] Driven SE 0
Date: Mon, 29 Nov 2004 09:42:37 +0000 (GMT)
I would like to know as to how does the USB host drive SE 0 on the
bus. I mean the exact events those happen during driven SE 0. I also
want to know as to how the UTMI responds to generate SE 0 on its
LineState signal.
Regards,
Virendra.
Yahoo! India Matrimony: Find your partner online.
_______________________________________________
http://www.opencores.org/mailman/listinfo/usb
_________________________________________________________________
Hey there NRIs! Desi news, films, ‘n more! http://www.msn.co.in/nri/
Stay in the loop!
_______________________________________________
http://www.opencores.org/mailman/listinfo/us
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