[USRP-users] Computation engine clock rates

Matt Ettus matt at ettus.com
Thu Dec 11 13:24:58 EST 2014


To a first order, you can use any clock rate you like for computation
engines, either slower or faster than the bus clock.  However, if you go
too slowly, then your block can dribble data out to the rest of the system
and cause congestion.

If you need to have a really slow clock, you are probably better off
running the noc_shell and axi_wrapper at bus_clk rates and do your own
clock crossing within your logic to operate at a lower rate.

Matt

On Thu, Dec 11, 2014 at 6:16 AM, seb fenn via USRP-users <
usrp-users at lists.ettus.com> wrote:

> Hello
>
> Are there any constraints on the clock rates that can be used with CEs?
>
> In the rfnoc_ce_auto_inst.v example and x300_core.v I see that the CEs
> generally have their CE clocks connected to the 166.67MHz bus clock,
> although I think the radios use 200MHz for the CE clock.
>
> Can I use any clock I want for the ce_clk input, say 50MHz, or does going
> slower than the bus clock cause problems?
>
> Thanks in advance.
>
> Seb
>
>
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