[SI-LIST] Re: Ethernet PHY not linking

  • From: "Rose, Michael" <mrose@xxxxxxxxxxxxxxxxx>
  • To: Suresh Subramaniam <ssubram@xxxxxxxxxx>, steve weir <weirsi@xxxxxxxxxx>
  • Date: Sun, 24 Oct 2010 22:31:56 -0400

are you sure you advertising 100mbps to/from your link partner? What's the AN 
status? Is MDIX enabled? have you tried loopback?

Mike

________________________________________
From: si-list-bounce@xxxxxxxxxxxxx [si-list-bounce@xxxxxxxxxxxxx] On Behalf Of 
Suresh Subramaniam [ssubram@xxxxxxxxxx]
Sent: Sunday, October 24, 2010 4:32 PM
To: steve weir
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Ethernet PHY not linking

Steve

I wanted to throw in one additional piece of data.

Loopback with a five foot cable will link reliably at 1Gbps

The PHY is a Marvell 88e1111.

Thanks
Suresh

On Oct 24, 2010, at 1:28 PM, "steve weir" <weirsi@xxxxxxxxxx> wrote:

> Suresh 10Mbps Ethernet tolerates really severe signal and timing impairments. 
>  100Mbps Ethernet is fairly tolerant especially over short distances.  That 
> you cannot make 100Mbps Ethernet work speaks to very basic design mistakes.
>
> You could have any number of problems:
> * Return path discontinuities
> * Severe mode conversion problems
> * Noise injection from the return path, you have AVDD adjacent to DVDD
> * Poor power quality at your transmitter and/or receiver
> * A way out of spec clock either basic frequency and/or jitter
>
> Steve.
>
>
> Suresh Subramaniam wrote:
>> Hello Experts,
>>
>> I am facing the following situation:
>>
>>
>> We have a tri-mode Ethernet PHY on one of our boards. It will reliably
>> link at 10Mbps but fails 100MBps and 1Gbps. The schematics have been
>> verified for correctness and the PHY configuration bits are strapped
>> properly on the board . RESET meets the timing specs defined in the
>> datasheet.
>>
>> The RJ-45 connector has integrated magnetics. The MDI* diff pairs out to
>> the connector are routed on the lower layers in the stackup (the last
>> five layers are reproduced below). Couple of pairs are routed on Sig4
>> and two other pairs are routed on Sig5.
>>
>> GND
>>
>> SIG4
>>
>> PWR5
>>
>> SIG5
>>
>> GND
>>
>>
>> The traces are about 0.5 inches in length. DVDD is a small plane on SIG4
>> and powers the core of the chip. AVDD is a small plane on SIG 5 and
>> supplies analog power. PWR5 is a 3.3V power plane (note that the
>> signaling voltage is 2.5V which is on a different layer). The 3.3V power
>> plane is pulled back around the RJ-45 making the MDI* diff pairs without
>> a reference plane on one side for about 100 mils.
>>
>>
>> I understand that the layout is not ideal. But can these deviations from
>> the ideal cause the link to fail at 100Mbps and 1000Mbps.
>>
>> Appreciate any pointers and insights you can offer.
>>
>>
>> Thanks
>>
>> Suresh Subramaniam
>>
>>
>>
>>
>> ------------------------------------------------------------------
>> To unsubscribe from si-list:
>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>>
>> or to administer your membership from a web page, go to:
>> //www.freelists.org/webpage/si-list
>>
>> For help:
>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>>
>>
>> List technical documents are available at:
>>                http://www.si-list.net
>>
>> List archives are viewable at:             
>> //www.freelists.org/archives/si-list
>> Old (prior to June 6, 2001) list archives are viewable at:
>>        http://www.qsl.net/wb6tpu
>>
>>
>>
>
>
> --
> Steve Weir
> IPBLOX, LLC 150 N. Center St. #211
> Reno, NV  89501 www.ipblox.com
>
> (775) 299-4236 Business
> (866) 675-4630 Toll-free
> (707) 780-1951 Fax
>
>
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field


List technical documents are available at:
                http://www.si-list.net

List archives are viewable at:
                //www.freelists.org/archives/si-list

Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu

_______________________________________________________________________
This e-mail and any files transmitted with it are proprietary and intended 
solely for the use of the individual or entity to whom they are addressed. If 
you have reason to believe that you have received this e-mail in error, please 
notify the sender and destroy this email and any attached files. Please note 
that any views or opinions presented in this e-mail are solely those of the 
author and do not necessarily represent those of the Curtiss-Wright Corporation 
or any of its subsidiaries.  Documents attached hereto may contain technology 
subject to government export regulations. Recipient is solely responsible for 
ensuring that any re-export, transfer or disclosure of this information is in 
accordance with applicable government export regulations.  The recipient should 
check this e-mail and any attachments for the presence of viruses. 
Curtiss-Wright Corporation and its subsidiaries accept no liability for any 
damage caused by any virus transmitted by this e-mail.
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field


List technical documents are available at:
                http://www.si-list.net

List archives are viewable at:     
                //www.freelists.org/archives/si-list
 
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu
  

Other related posts: