ICC timing report -from clock

[muromir]

Hello everyone,
I have a design with a few generated clock and some data paths between the different clock groups. When I try to report the timing between two clock groups with

report_timing -from Clk2 -to Clk1

I do not get some existing paths, no matter how many max_path and nworst I set. On the other hand, when I report the timing directly from the cells I am intersed in

report_timing -from I2/* -to Clk1

I see the path, but then the report shows me, that the launching cell is being clocked by a clock, called Clk2' (with an apostrophe after it) :

Startpoint: I2/Z_reg[7]
(rising edge-triggered flip-flop clocked by Clk2')

So my question is what exactly this apostrophe means, because apparently this has something to do with the behaviour of my report.

Best Regards

 

[phoenyxu]

apostrophe measn clock source is fall edge. In other word , there are odd inverter function cells b/t source source and your launch ff's clock pin.

can you try report_timing -from [get_clocks Clk2] -to [get_clocks Clk1] , any path exported?


Phoeny
BR

 

[muromir]

Thanks for the answer. This is definitely the case - there is an inverter on the clock path. I did try to report with the get_clocks command as you suggested but the result is still the same. Apparently there is some other reason why this path is fragmented. Thank you anyways !

 

[phoenyxu]

another possible reason for report_timing -from clock can't output timing path is that the slack is positive of path -from I2/* -to Clk1. report_timing -from Clk2 -to Clk1 -slack_less_than maybe help u. good luck

Thanks for the answer. This is definitely the case - there is an inverter on the clock path. I did try to report with the get_clocks command as you suggested but the result is still the same. Apparently there is some other reason why this path is fragmented. Thank you anyways !

 

[sameer_dlh25]

Is this path is met with large timing margin ?