[U-Boot-Users] SCC3 with very slow ethernet connection

Franca, Jose Filipe (ext) jose.franca.ext at siemens.com
Sat Mar 11 12:21:35 CET 2006

We are using the same debug module (based on a LXT905, with a schematic similar to the application note from the manufacturer) as we used in another board and it works fine. No report of such problems.
The lines to the mpc follow the same schema as in a similar board... Unfortunatly we can't compare the two configurations, because currently we don't have access to such code.
In the meanwhile, i've enabled the full duplex mode and still have the same problem... Did anyone noticed that when enabling full duplex, there is no enable for internal loopback? (As stated in the reference manual of the processor) Or is it not necessary?


De: u-boot-users-admin at lists.sourceforge.net em nome de Jerry Van Baren
Enviada: sex 10-03-2006 21:24
Para: u-boot-users at lists.sourceforge.net
Assunto: Re: [U-Boot-Users] SCC3 with very slow ethernet connection

Franca, Jose Filipe (ext) wrote:
> Hello u all!
>       I have a mpc8247 based board, with the following ethernet configuration:


>       The result of this is a slow SCC3 ethernet connection. I've checked all the steps listed in the mpc8272 reference manual and everything seems to be by the book...
>       From snifing around with ethereal, i've noticed that the frames seem to be passed nicely. But, sometimes there are some frames that aren't received and i get bit 11 asserted  (NO Rx nonoctet-aligned frame. Set when a frame containing a number of bits not divisible by eight is received. Also, the CRC check that occurs at the preceding byte boundary generated an error.).
>       What am i missing here?  Any ideas?
>       Thanks a lot for reading! Many more if you reply :)
> Best regards,
> Filipe França.

Hardware problem?  Sounds like noise in the ethernet receive subsystem.
  Do you have proper (impedance controlled and low noise) routing
between the RJ-45, transformer, and the PHY?  Are the lines terminated
properly at the transformer?


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