Hi all,
I am trying to add a custom RFNoC block and my block runs on different
clocks(not the default ones). So I followed the instructions from the FAQ
page in RFNoC wiki of deriving clocks from the available clocks -
https://kb.ettus.com/RFNoC_Frequently_Asked_Questions#How_do_I_add_a_clock_with_a_different_frequency.3F
But when I add the parameters in block YAML, it added new ports to my
*rfnoc_block_myblock* module, which is not what I expected. My intention
was to derive 2 clocks from the rfnoc_chdr_clk  and use it inside my block.
For this I added the clock IP module (instantiated) in the
noc_shell_myblock, because this is where the CDC FIFOs are there. So, with
this method the generated clock just stays inside my block and won't be
available outside to it. Maybe the steps described in the FAQ might not be
the right way to go about with my requirement? I am not sure.

Also, I tried not adding the YAML parameters of the clocks for my block.
This worked to the point where the implementation of the entire design
failed with WNS of -0.8ns on the new derived clock I added. I also got a
few Critical warnings for the clocks I added, not sure if it is related
somehow or if I can ignore it -



*TIMING-4#1 Critical WarningInvalid primary clock redefinition on a clock
tree  Invalid clock redefinition on a clock tree. The primary clock
x4xx_core_i/rfnoc_image_core_i/b_myblock_3/noc_shell_myblock_i/clk_wiz_chdr_200_125_inst/inst/clk_in_chdr
is defined downstream of clock clk200 and overrides its insertion delay
and/or waveform definition. *

I followed this thread (
https://www.mail-archive.com/usrp-users%40lists.ettus.com/msg14663.html) to
add IPs of my clock module that I generated with with Vivado IP catalog and
copied the *.xci, .v* and other generated files into the
path/to/module/rfnoc/fpga/myblock/ip/ and changed the Makefile and block
YAML definitions like the example given in the example Gain block.

I checked the timing summary report and I found that the violation happens
in the derived clock that connects to one of my blocks. I was able to build
the IP by itself when I was testing it for viability.

Any tips or leads in adding custom derived clocks to the design would be
super helpful and thank you all for maintaining such a nice community!!
-J
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