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Altera_Forum's avatar
Altera_Forum
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13 years ago

Setting i/o pins to tri-state mode.

I am a newbie. I am using a board with a Cyclone II, To prevent the board from getting excessively hot, I need to set all I/o pins to tri-state mode. How do I do that?

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    13 years ago

    In Quartus, with your project open, go to 'Assignments' -> 'Device'.

    Click on 'Device and Pin Options'. In the left tab select 'Unused Pins'.

    Reserve all unused pins 'As input tri-stated' - (with or without bus-hold/pull-ups as necessary).

    Cyclone II projects seem to default to 'As output driving ground'. Good for noise immunity, not particularly appropriate for development boards.
  • Altera_Forum's avatar
    Altera_Forum
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    13 years ago

    If FPGA is configured with a "bad" design, to prevent excesive hot, you can temporarly pull down (1k resistor) the nconfig pin usually pin# 5 on Active Serial connector.