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zjj
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2 hours ago

recovery timing issue

I am working on Agilex 7 FPGA with quartus 25.3 software.  in my project, I use the asynchronous reset and sync de-asserted stragegies.  and I add the rst synczer circuit for each sub module in the top.

background:  clk freq is 416Mhz;  all design use asynchronous reset; 

after fitting all design, the timing report about recovery violation has -1.8ns. 

for one timing path,  the start point is reset_sync flop2,  the end point is aclr port of one flop in the module B. from the following figure 1,  I find the distance  start point  and end point is not far apart but the routing delay is nearly 4.386ns.   and How I fix the timing?  Doesn't the reset route go through global network?  

figure 1:

for compasion,I have taken the follwoing screenshot of the common path routing as figure 2

here,  the path from start point pll to clk port of reset_sync flop spans nearly the fabric fpga, but the actual routing delay is only 4.04ns.

figure 2:

 

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