Hi Rob, RFNoC doesn't support generating user clocks for you yet (the range value is not currently used). You could use the `dram` clock on N310 and connect that to the `ce` inputs of your blocks. That should be about 300 MHz. The `rfnoc_chdr` clock is 200 MHz on N310.
If it won't close timing with the dram clock, and you want something slower, then you can modify the HDL to add the clock you want. Take a look at n3xx_clocking.v. You could probably modify the misc_clock_gen IP block to add a clock closer to 260 MHz. You'd then have to route that clock into n3xx_core then rfnoc_image_core, and add the new clock to n310_bsp.yml for the rfnoc_image_builder to generate code to use it. Adding custom clocks is a pretty manual process at the moment. Wade On Wed, Feb 23, 2022 at 10:15 PM Rob Kossler <rkoss...@nd.edu> wrote: > Hi, > I have a signal processing block that includes a zero-padded FFT (50% > zeros) that I built for the N310. Because of the throttling that occurs > during insertion of zeros, I expect that my FFT will need to be clocked at > a bit more than twice the max sample rate. So, since I want to operate the > N310 at the highest sample rate of 125 MS/s, it seems that my FFT will need > to be clocked >= 260 MHz. I'm wondering how to do it. > > I've looked at the RFNoC specification and my block is already set up to > use the "CE" clock for both control & data. In the rfnoc spec, it mentions > that I can enter a "range" for my clock in the block definition yaml. But, > I also see that in the end, the top N310 yaml will require me to map a > _device clock to my block's CE clock port. > > It's not clear to me how this works. Does it help to provide a range in > the block definition yaml? Or, perhaps it is even necessary? How do I > specify in the top N310 yaml which device clock will map to my blocks CE > clock port? It seems to me that I am missing a step (defining a clock > somewhere?). > > I am pretty much a novice, so I expect that this is the cause of my > confusion. I am even struggling to figure out what the current clock rates > are (rfnoc_ctrl, rfnoc_chdr, ce, etc) and where they are defined. Any help > would be appreciated. > Rob > _______________________________________________ > USRP-users mailing list -- usrp-users@lists.ettus.com > To unsubscribe send an email to usrp-users-le...@lists.ettus.com >
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