On Tue, Aug 11, 2020 at 6:18 AM Daniel Ozer via USRP-users <
usrp-users@lists.ettus.com> wrote:
> Hi everyone,
> Im just started developing on the usrp X310 platform and i have some
> questions :
>
> 1. Is the crossbar is capable to transfer data between 2 rfnoc blocks at
> maximum rate of the crossbar clock ?(bus_clk=187.5MHZ)
>
Yes. Each port can handle 200MHz worth of bandwidth, but it cannot handle
full bandwidth from both radios at the same time. You'd need multiple
crossbar ports for that.
>
> 2. if i have this theoretical chain : rfnoc: block1 -> rfnoc: block2 ->
> rfnoc: block3 -> rfnoc: block4
> Is every block can send data to the next block at the maximum rate of the
> crossbar clk ?
>
Yes. The crossbar acts as a switch.
>
> 3. I have a chain : rfnoc: signal source -> rfnoc: DUC (1M to 200M) ->
> rfnoc:radio_block.
> how is it possible that the connection between the duc and the radio block
> doesn't throw an error because the transfer rate is bigger than the clk
> speed of the crossbar ?
>
The bus widths are different between the two domains. Most everything on
ce_clk is 32-bit IQ samples, whereas the bus_clk domain is 64-bits wide.
>
> 4. Is it possible to change the crossbar clk to ce_clk=214MHZ instead of
> bus clk ?
>
Maybe, but what would be the point? You'll probably end up not being able
to close timing on the design, but that's just a guess.
>
> 5. I saw in the article (" Measured Latency Introduced by RFNoC
> Architecture" )that the nocshell and the axi wrapper have a big latency
> (100nanosec and 1.7microsec) . There is a way to drop down the latency ?
>
I don't know how to address this. Maybe a link to the article and to
figure out where the "large" latencies are? What is your target latency?
Brian
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