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Posted by MM on July 31, 2008, 1:08 pm
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Thank you for your help. I have two scenarios. In one I read all ones from
all the MDIO registers, so in other words the chip seems to be in some bad
state, and nothing can be done to revive it through software. This condition
seems to depend on power-up and it could be a separate problem. In another
scenario I can read/write MDIO registers fine however the link is not
established. I know that the problem is on my side because a) the same card
might work/not work without changing anything on the other side, and b) I
can take another of my cards from the same batch and it will work...
/Mikhail
> An obvious first step would be to read the PHY's status registers through
> MDIO.
>
> You need to check whether the capabilities you are advertising are
> compatible with the PHY at the other side and whether the other side is
> negotiating at all. You also need to check you are setting your PHY to
> operate in accordance with the AN resolution function. Check that speed
> and full/half-duplex have been set appropriately after AN completes.
>
> Full/half-duplex needs the MAC to be configured properly.
>
> Arthur.
>
>> Hi all,
>>
>> I have a design with a tri-speed Base-T PHY, which exhibits some weird
>> behaviour. For some reason sometimes the PHY doesn't establish the link
>> with another PHY (typically in a PC) after the auto-negotiation. Some of
>> my boards almost never fail, while others fail much more frequently.
>>
>> I was wondering how people debug this kind of problems. Is there anything
>> I can look up with a basic 500 MHz scope? Is there a low level protocol
>> tester I could rent?
>>
>>
>> Thanks,
>> /Mikhail
>>
>
>
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