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Message
From: Virendra<virendradhavale@y...>
Date: Tue Nov 23 06:16:07 CET 2004
Subject: [usb] Device Connect detection
Hi Kingfischer,
If you are using the standard UTMI interface then it has a 2 bit output called LineState. This signal replicates the actual DP and DM lines.
When the device gets attached, the pull - up on DP line will be connected to Vcc thus, producing a J state on the DP - DM lines. This state gets replicated on the LineState signal of the UTMI which tell the device that it has got connected.
I hope this explanation answers your question.
Regards,
Virendra.
kingfischer@r... wrote:
Hi,
I am designing a USB 2.0 Device Controller with a UTMI interface,
assuming that I will be purchasing a PHY Chip which is UTMI compliant.
My question is about how the device knows if it is connected to the USB
hub/port. The answer I presume is that the device checks the V+ line
and if powered assumes that it is connected.
In my case my device controller connects via the UTMI interface to the
PHY....unfortunately there is no signal comming out of the PHY which
signals a device connect or a power up. ( absence of ..say..power-on
reset).
I need to know this point of device connection as I must send a reset to
my device logic and also reset the PHY.
Another way of asking the same question would be ,
With reference to the UTMI 1.0 Specifications on Page 52 , where does
the device_reset signal come from ?
Hope to get some clarification.
Regards
Kingfischer.
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