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Altera_Forum
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12 years ago

Schematic highs and lows

Are there any simple ways to force a schematic signal to logic HIGH other than tying it to VCC symbol? How about forcing a logic LOW other than tying to a GND symbol?

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  • Altera_Forum's avatar
    Altera_Forum
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    --- Quote Start ---

    Are there any simple ways to force a schematic signal to logic HIGH other than tying it to VCC symbol? How about forcing a logic LOW other than tying to a GND symbol?

    --- Quote End ---

    The you mentioned above is the simplest way. Also, you can define a middle signal which is connected to VCC or GND, then you can use this middle signal as the high or low.
  • Altera_Forum's avatar
    Altera_Forum
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    I think what Jerry meant was that you could connect a net to VCC or GND and call it something like LOGIC_HIGH. Then label any net you want connected to it also LOGIC_HIGH.

    As a quick reference, if you were using HDL, connecting to high or low is as simple as:

    some_sig <= '1';
  • Altera_Forum's avatar
    Altera_Forum
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    --- Quote Start ---

    I think what Jerry meant was that you could connect a net to VCC or GND and call it something like LOGIC_HIGH. Then label any net you want connected to it also LOGIC_HIGH.

    As a quick reference, if you were using HDL, connecting to high or low is as simple as:

    some_sig <= '1';

    --- Quote End ---

    Yes, as attached image shows!
  • Altera_Forum's avatar
    Altera_Forum
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    hmmm... not sure the thumbnail is technically legal since the VCC and GND are single signals (although it may still work). It would be OK for that purpose, but for a bus I would use the primitive lpm_constant.

  • Altera_Forum's avatar
    Altera_Forum
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    You can connect a bus to GND/VCC without a problem.

    Any reason you're using schematics and not HDL?
  • Altera_Forum's avatar
    Altera_Forum
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    Just an old-timer doing some relatively frequency and pulse generation - 24 programmable counters and one-shots. Easier for me to do in schematics (the ldm_xxx Megafunctions work great) then trying to control synchronized counters in HDL.