Re: [Discuss-gnuradio] Run time FIFO error

[Tim Newman]

It's hard to tell in the pcap file where it gets lost.  I'm not using a dissector for the UHD packets so I can't see whats in the data field, thus I can't match up commands coming/going.  I have confirmed that this issue does not exist when I'm using 003.004.X firmware and fpga load.

Tim

On Fri, Jun 21, 2013 at 1:18 PM, Josh Blum <address@hidden> wrote:

On 06/21/2013 09:41 AM, Tim Newman wrote:
> Yes, bringing this back up. Back to the original topic.  When I get this
> FIFO ctrl error, the host is sending back an icmp port unreachable msg to
> the usrp, I grab this using wireshark.
>

Well if the app shutdown from the error. That could be the host's
response to a stray packet coming from the USRP after the socket was
closed. For example a UDP packet w/ a GPSDO NMEA message. So this ICMP
error may not be indicative of anything.

> All I'm doing is running "uhd_usrp_probe".  I've tried with and without
> adding the --args addr=<ip> parameter, same thing using both.
>
> I've debugged a bit, and increased the ACK_TIMEOUT in
> usrp/usrp2/usrp2_fifo_ctrl.cpp from 0.5 to 10.0 and it literally just sits
> at:
>
> Creating the usrp device with: ...
> -- Opening a USRP2/N-Series device...
> -- Current recv frame size: 1472 bytes
> -- Current send frame size: 1472 bytes
> <sits here for 10 seconds>
>
> Then spits out
> RuntimeError: RuntimeError: fifo ctrl timed out looking for acks
>
> Again, there is a switch in between the USRP and the host.
>

Yup, definitely a lost packet. Its gone and more time isnt going to
help. Question is, where is the packet lost? We have a control packet
from host to switch, then switch to USRP. Then a response packet from
USRP to switch, then switch to host.

-josh

> Tim
>
>
> On Thu, Jun 13, 2013 at 12:27 AM, Sean Nowlan
> <address@hidden>wrote:
>
>> I think 512 is the max value for N on N200/N210 hence 195kSps is minimum
>> sample rate.
>>
>>
>> Karan Talasila <address@hidden> wrote:
>>
>> @sean can you please tell me how you got minimum sampling rate for usrp
>> N210 as 100*e6/512. I know that the sampling rate should be 100*e6/N where
>> N is an integer. So N can be any integer even greater than 512 right. In
>> that way, what is the minimum that the USRP accepts. what is maximum N that
>> can be used.
>>
>>
>> On Thu, Jun 13, 2013 at 6:20 AM, Sean Nowlan <address@hidden>wrote:
>>
>>> On 06/12/2013 08:49 PM, Marcus D. Leech wrote:
>>>
>>>> On 06/12/2013 08:29 PM, Sean Nowlan wrote:
>>>>
>>>>>
>>>>> The minimum "reasonable" sample rate I've used is 2e5 (100e6/2e5 =
>>>>> 500). I think 100e6/512 = 195312.5 is the smallest supported rate.
>>>>>
>>>>>  Yup, sorry, you're right.  I tend to pick values that are valid for
>>>> both 64Msps and 100Msps master clock rates, since I write apps that need to
>>>> be reasonably
>>>>   agnostic with respect to hardware.
>>>>
>>>>
>>>>  Ah, makes sense.
>>>
>>>
>>>>
>>>>
>>>

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>>
>>
>>
>> --
>> Regards
>> Karan Talasila
>>
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