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Novice
99 Views

Setting output delay

Hello,

 

I want to constrain my system (attached) for input and output delays.

The input delay is straightforward. But I have my doubts about the output delay.

 

This is what I did for the input delay:

 

create_clock -name clock_in -period 10.000 [get_ports {clock_in}]

set_input_delay -clock clock_in -max 1.0 [get_ports data_in] 

set_input_delay -clock clock_in -min 0.1 [get_ports data_in] 

 

Now, what should I do to specify the output delay ?

What clock should be used for reference ?

 

clock_in ?

 

set_output_delay -clock clock_in -max -1.0 [get_ports data_out]

set_output_delay -clock clock_in -min -0.1 [get_ports data_out]

 

Or clock_out ?

 

Now, what should I do to specify the output delay ?

 

set_output_delay -clock clock_out -max -1.0 [get_ports data_out]

set_output_delay -clock clock_out -min -0.1 [get_ports data_out]

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12 Replies
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Retired Employee
7 Views

You have created a single data rate source synchronous interface, so you have to create a generated output clock as the reference clock. See this online training for the details:

 

Constraining Source Synchronous Interfaces

 

#iwork4intel

Highlighted
Novice
7 Views

So I should first use the "create_generated_clock" command like this:

create_generated_clock -name clock_out -source [get_ports {clock_in}] [get_ports {clock_out}]

And then use the the generated clock as reference:

set_output_delay -clock clock_out -max -1.0 [get_ports data_out] set_output_delay -clock clock_out -min -0.1 [get_ports data_out]

Correct ?

 

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Highlighted
Retired Employee
7 Views

Yes, that looks good. Your max and min values should of course be based on the timing requirements of the "downstream" device that you are connecting to, and usually those values (or at least not both of them) aren't negative. Do you have setup/hold info or skew info for the downstream device?

 

#iwork4intel

Highlighted
Novice
7 Views

Thanks,

That was a theoretical question - so the actual setup/hold times aren't relevant.

 

Is there another lecture on DDR interfaces ?

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Highlighted
Retired Employee
7 Views

Highlighted
Novice
7 Views

Thanks.

If any Intel employee sees this - both lectures don't work well when they're downloaded as a zip file.

It launches, you can hear the speech - but the slides don't show on the screen.

On the web it works fine.

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Highlighted
Moderator
7 Views

Hi Shai Kon,

 

We was able to see this as well. we will get our Intel IT to fix this .

 

Thanks

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Highlighted
Retired Employee
7 Views

In the .zip file, run Launch_Presentation.exe. This will run the training. The instructions supplied when you registered should have mentioned this.

 

#iwork4intel

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Highlighted
Moderator
7 Views

Steve was right, I will had our IT to have a readme.txt files for enhancment.

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Highlighted
Novice
7 Views

There is NO file named Launch_Presentation.exe in the zipped archive

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Highlighted
Retired Employee
7 Views

I just realized these are older trainings that don't include the Launch_Presentation.exe executable. As such, use the presentation_html5.html file (instead of presentation.html) to run these trainings in a modern browser (without Flash).

 

#iwork4intel

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Highlighted
Moderator
7 Views

Sorry, what I mean is click on

 

launcher.html

 

It work from my side.

 

 

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