Hey Jeff,

at first glance, it looks like you're doing it all right. What's the
size of your input buffer on your custom DUC? Also, can you post a full
log of the streamer setup?

-- M

On 01/09/2018 08:41 AM, Long, Jeffrey P. via USRP-users wrote:
> Looking for some advice and help on RFNOC….
> 
>  
> 
> I am creating a custom RFNOC block that will roughly do what the
> noc_block_duc does but instead uses a fractional polyphase interpolator.
> I believe I have everything working correctly in terms of the tlast and
> EOB and for single timed bursts it seems to work fine which I can verify
> on the scope and in chipscope. However when I switch to a streaming data
> I start getting UUs. If I look at it in chipscope it appears that the
> incoming data is just not being supplied fast enough. My block is not
> pushing back. In terms of rates I am using a 1 gig Ethernet connection
> and am running 32 times interpolation in my block with the radio block
> being set to 200 MHz. This would imply that I have a 6.25Msps required
> feed rate to my block. I think this should be well within the 1 gig
> capability. Again I verified that my block is not pushing back so it
> really appears the data is not coming down fast enough. My rfnoc graph
> consists of the radio core connected to my block and then to the host.
> Nothing else.
> 
>  
> 
> I am wondering are there flow control things that I am not doing
> properly in my block. Perhaps the host UHD code is not getting the right
> feedback for the flow control? Perhaps sample line rate settings that I
> should be doing? In my UHD code I am only setting the sample rate in the
> radio core and it only accepts 200 MHz but does that somehow screw up
> the flow control? Is there special sauce in the duc that makes it
> necessary to use that with the radio core to get the rates correct?
> 
>  
> 
> Thanks for any help.
> 
>  
> 
> Jeff
> 
> 
> 
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> 


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