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Altera_Forum's avatar
Altera_Forum
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18 years ago

set_attribute DRIVE

Hi, I would like to set the following attribute:

set_attribute -name DRIVE -value "<drive strength in mA>" -port <port name>

The compiler doesn't accept this attribute when I write it in my .sdc file.

I wrote following:

set_attribute -name DRIVE -value 12 -port MY_PORT

Does anybody know if this writing is correct?

Thanks!

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    18 years ago

    Where did you find the documentation on "set_attribute -name DRIVE"? I found it only in the Mentor Precision chapter of the Quartus handbook. Are you using Precision, or is your Question for TimeQuest? The Synopsys Design Constraint file mentioned in the Precision chapter is not the TimeQuest Synopsys Design Constraint file.

  • Altera_Forum's avatar
    Altera_Forum
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    18 years ago

    the sdc file is for setting timequest timing constraints.

    You need to place the set_attribute in the quartus project file.

    Easiest way to do that is with the constraints editor.
  • Altera_Forum's avatar
    Altera_Forum
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    18 years ago

    I'm looking for an TimeQuest constraint to change the I/O drive strength and the slew from the I/O. I can change the drive strength in the Chip Planner but I'm looking for an constraint which I can write into my .sdc file.

  • Altera_Forum's avatar
    Altera_Forum
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    18 years ago

    --- Quote Start ---

    You need to place the set_attribute in the quartus project file.

    Easiest way to do that is with the constraints editor.

    --- Quote End ---

    I think what Avatar had in mind was using the Assignment Editor to enter set_instance_assignment (not set_attribute) lines in the Quartus settings file, or .qsf (not the Quartus project file, or .qpf).

    As Avatar said, the TimeQuest .sdc file has timing constraints and exceptions. Device settings, even those affecting timing, are Quartus settings in the .qsf file.

    --- Quote Start ---

    I'm looking for an TimeQuest constraint to change the I/O drive strength and the slew from the I/O. I can change the drive strength in the Chip Planner but I'm looking for an constraint which I can write into my .sdc file.

    --- Quote End ---

    If you made a change in the Chip Planner or Resource Property Editor without making the change in the .qsf, then you can use the ECO flow to get the change into the Quartus database so that TimeQuest will see it when you open the project in TimeQuest. The ECO flow is documented in the Quartus handbook Volume 2, Section IV, Chapter 14. You might just have to do "Check and Save All Netlist Changes" in the Resource Property Editor, but refer to the handbook to see whether there are any other required steps.

    There are some settings that can be changed in the .qsf and then used by TimeQuest without recompiling first. The Quartus help page for create_timing_netlist says, "Use '-force_dat' to rerun delay annotation. This is required if any delay annotation setting is changed in the Quartus II project revision (e.g. OUTPUT_PIN_LOAD)." I don't know whether -force_dat will make TimeQuest see a change to a Current Strength or Slew Rate setting in the .qsf without first compiling.