How to change use clock on nets?

You may want to consider the "bufferTreeSynthesis" command instead of using CTS.  It build balanced buffer trees without faking the tool out into thinking the net is a clock.

That said here are a couple of approaches to relieve the clock property on these nets:

For each of the nets, use dbSet to set the "isCTSClock" bit to 0.  For example:
dbSet [dbGet -p top.nets.name *clk*].isCTSClock 0

If you're using an older version of Encounter where isCTSClock isn't an exposed dbGet field you could do the same with older FE-TCL style commands:

foreach net $netList {
  dbSetIsNetDefInClock $net 0
}

Great question!  Let us know how it goes.

Hope this helps,
Bob

Hi Bob,

thank u for u r reply.

I am working on a hierarchical design. I need to do buffering on nets across partitions. i have written some db scripts to get startpin and corresponding endpn and used cts spec as shown below(no need of balancing b/w nets). i preffer CTS than BTS as CTS takes less run time.

AutoCTSRootPin core/*/startpin
SetDPinAsSync YES
RootInputTran  100.0ps
MinDelay       300.0ps
MaxDelay       800.0ps
MaxSkew        250.0ps
SinkMaxTran    100.0ps
BufMaxTran     100.0ps
Buffer         BFX71
#
NoGating       NO
LeafPin
+ core/*/endpin

.............................

once it was over i cleared the spec. and read the actual clock spec.

i need to find all nets created by above CTS and change its property to signal.

Regards,

suresh

Hi Bob.

          I inserted clock buffers on some clk nets using ecoAddRepeater, but the new nets after the buffer insertion r not getting the use clk property. can u please tell how i can replicate the clk property for new nets also. Also can u please explain how encounter usually assigns this clock property on nets. please reply as soon as possible.

Regards,

suresh

This blog entry on clock net markings might be helpful.

/blogs/di/archive/2008/08/20/understanding-clock-net-markings-in-soc-encounter.aspx

There's some good comments there too about nuances related to clock net markings.

If you load a clock tree spec file and trigger a trace you might be able to get CTS to re-apply the markings.  Another approach is to write the clock tracing to a file, parse it, and apply the clock net markings for each net in the file.

Hope this helps,
Bob

Hi Bob,

               I loaded the clokspec and used the following cmd

ckSynthesis -check -forceReconvergent -trace

the property on the eco nets in the clk path not updated. but the report file after tracing contains these eco net names.

can u please tell how to set clock propery on these nets? 

Regards

suresh 

Use:
dbSet [dbGetNetByName <net_name>].isCTSClock 1

I'll do some testing to see if there's a way to get CTS to automatically trigger the markings based on what it traces.  I'll let you know what I find.

-Bob