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HolySaint
Joined: 31 Aug 2008
Posts: 68
Helped: 1
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 06 Oct 2008 12:33 about dft signal |
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i have a clock named clk
after some logic i got some other clocks, just like clk2, clk3......
when i set dft signal , do i need to add clk2, clk3...
??
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rameshsuthapalli
Joined: 27 Jun 2006
Posts: 163
Helped: 19
Location: bangalore,india
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| 07 Oct 2008 9:16 about dft signal |
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Hi,
in DFT insertion the clock definition is based on your sepc.if you want to use single clock as a scan clock u can define that clock "clk" as u r scan clock and the tool will fix the "clk2", "clk3" with the "clk" in dft mode. The clk should be a primary input.
if you wants to have 3 diffrent scan clocks u can declar the clk,clk2,clk3 as scan clocks the tool will not fix the clk2,clk3 logic with the "clk".
what ever the clocks u define as scan clock should be an input.
Thanks,
ramesh
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HolySaint
Joined: 31 Aug 2008
Posts: 68
Helped: 1
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| 07 Oct 2008 11:12 about dft signal |
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i know
but when the clk2 is a pin, an has nothing to do with clk(port), what should i do?
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sunilbudumuru
Joined: 08 Oct 2008
Posts: 8
Helped: 3
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| 08 Oct 2008 9:51 about dft signal |
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hi,
As you know DFT tools are smart enough to fix clock related issues.
Make sure of following points.
1. Make sure that all flops will be controlable with the scan clk, ("clk" in your case). As far as all the scan flops in your design got "clk" as scan clock (all flops should be controllable with your "clk"), you dont find any clock related issues else you will see issues with the scan insertion.
2. If clk2, clk3 .. are generated clocks from "clk", just bypass the generated clocks with the scan clock ("clk" in your case).
3. It is preferred not to use multiple clocks as scan clocks instead use a single clock as scan clock unless your DFT requirements demands multiple scan clocks.
Hope you've got an idea.
Regards,
SunilB.
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