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Altera_Forum's avatar
Altera_Forum
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15 years ago

why warning "Missing drive strength" ?

Hello all,

I am a beginner of Altera FPGA. Today I wrote a simple project with Quartus II 10.0. I set the device as EP3C25, then I wrote a simple VHDL, assigned the location and IO standard. When I compile this project, I always got a warning:"Some pins have incomplete I/O assignments. Refer to the I/O Assignment Warnings report for details". I check the assignment waring report, and all out pins are identified as "missing drive strength".

I changed the device to EP1C12, reassign the location, the warning is eliminated. I did some tests, and found that if I use Cyclone III device, this warning will come out. Could anybody tell me why?

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    Drive strenght is the maximum current that the pin can drive.

    In modern FPGA this is programmbale.

    If you don't set the value you get a warning saying that a default value (probably the highest current) has been set.

    This is not a problem unless you don't have signal integrity problems

    in the integration of your FPGA on the final board.

    I think that when you don't get the warning is because the value is not programmable
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    --- Quote Start ---

    Thank you. Could you tell how to program the drive strength?

    --- Quote End ---

    In the pin planner in the pin list there's a column called current strength.

    If it doesn't show up there, right-click your mouse in the pin list and select customize columns.... You can add the currenth strenght column and select the desired drive strength.

    good luck, Ton
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    The warning is eliminated when I did what you told me to do.Thank you.