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LPM DIVIDE latency

qd0090
Beginner
566 Views

hi everyone:

 i want to use  LPM DIVIDE in max 10, and i use quartus prime 16.1, the clk is 96MHz

but i did not found information about the latency of    LPM DIVIDE ,  so i do not know how many clks should i wait to get the right outputs

 

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8 Replies
qd0090
Beginner
564 Views
 

lpm_divide.png

this is my lpm divide block

numer unsigned 21 bits

denom unsigned 12 bits 

i use signal tab to monitor the latency,

but i find the latency changes from 2clk(20.8ns)  to 5clk (52ns)

i want to know the max latency

thanks!

Kenny_Tan
Moderator
557 Views

Usually, what we do is use the modelsim to simulate the RTL behavior of the design first.

Then constrain the design and make sure the timing closed.

From there, you should be able to see the latency in the Timing reports.


This latency should not be vary so much. If you look into the modelsim simulation, you will see usually, it take about one cycle of input clock to do the operation.


qd0090
Beginner
552 Views

i test the latency in signaltab,   sometimes is 4 clks.

lpm_divide.png

how to constrain the lpm divide?

Kenny_Tan
Moderator
542 Views

why don't you attached your design.qar here for us to take a look?


You may take a look this video for constrain a design


https://www.youtube.com/watch?v=hfaiPxl9Z9A


qd0090
Beginner
535 Views

hi

this is my project.

i do not know what constraints should i use

multicycle path?

max delay?

thanks!

Kenny_Tan
Moderator
525 Views

What I try is simulate your design in the rtl simulator vwf files. I dont see any output, can you try it on your side? You can bring out the *vwf files with file -> new -> vwf files.


https://www.youtube.com/watch?v=RU4LU1nokwg


You dont need to set the multicycle path for now, after you make sure your rtl simulation behavior, only you set the multicycle.


Kenny_Tan
Moderator
514 Views

any update?


Kenny_Tan
Moderator
492 Views

We do not receive any response from you to the previous reply that we have provided. Please post a response in the next 15 days to allow me to continue to support you. After 15 days, this thread will be transitioned to community support. The community users will be able to help you with your follow-up questions. 


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