Re: [Discuss-gnuradio] find_usrps "No USRP2 found."

[Jeff Brower]

Steve-

> Further to my problem trying to discover the USRP2. From a cold start
> (the USRP2 was left without power since my last posts) I configure the
> GigE port using ethtool and enable TX pause frames (this seems to be
> necessary magic on my PC). I then run this at the command line:
>
> while true; do clear; find_usrps; sleep 1; done
>
> and watch the output. For the first 30 seconds or so I get the device
> MAC address then "No USRP2 found." From a real cold start this takes a
> little longer so I got as far as running usrp2_fft.py -f 925M and that
> guarantees I lose connectivity. Have removed the power and lid on the
> USRP2 and see U12 which is a large-ish package and gingerly touch it. It
> is indeed quite hot. Once the device has stopped responding even
> removing the power for a few minutes is not enough to make it functional
> so a heat-related failure of the PHY chip seems plausible. Before I go
> about requesting a return authorization is there any other diagnostic I
> can perform?
>
> Many thanks to all (especially Marcus) for your help

U12 is the PHY.  PHYs tend to run somewhat hot, so likely what you're seeing is 
Ok.  But, with the top off, you could
try pointing a large fan at the chip, and see what happens again from cold 
start.  If the fan reduces the chip surface
temperature to the point where you can hold your finger there (at least for 30 
sec or so) and you still have the
connectivity issues, then you can rule out a chip/board/heat problem.

That's not saying something else hasn't gone wrong with your board, but it 
might help you to obtain consistent results
between "cold start" and "warm start" and make it easier to debug.

-Jeff

>> Marcus D. Leech wrote:
>>
>>> There were a batch of bad PHY chips, and I wonder if yours is one of them.
>>>
>>> U12, a DP83865 is the Gigabit PHY.   On "bad" versions of this chip,
>>> they run
>>>   *really hot*.  You could *gingerly* feel yours and see if it's really
>>> uncomfortably
>>>   hot.  If so, you likely have a bad PHY, in which case, it should be
>>> returned.
>>>
>>> They've been having occasional trouble with this PHY chip, and they pass
>>> the checks
>>>   but fail sometime later.
>>>
>>>
>>
>> Although I did get find_usrps working briefly (by enabling TX pause)  I
>> couldn't get any data into usrp2_fft.py.
>>
>> Repeating the steps I tried earlier just have it fail again. It is,
>> however, "forgetting" the tx pause flag - could that be a negotiation thing?
>>
>> I shall whip the cover off later and do as you suggest from a cold
>> start. If its a bad PHY then I shall make arrangements to return the USRP.
>>
>> Many thanks
>>
>> Steve
>>
>>
>>
>
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