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Altera_Forum's avatar
Altera_Forum
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17 years ago

may i use the global oe pin as the global reset pin?

the device i am working with is EPM570T5I, and and i need two reset pins,but the device just has one global reset pin,so i want to use the global oe pin as the global reset pin, and this works? another question: how to deal with the unused pin,set as tri-stated input pins? thanks!!

5 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    Global reset is an option, that acts similar to power-on-reset, if enabled. Most HDL designs have a user defined reset in the code, it can be triggered from any pin of your choice. Unused pins should have their weak-pullup resistor enabled to avoid increased device supplied current possibly caused by floating inputs. It's a global device option, that can be set for all unused pins.

  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    --- Quote Start ---

    Global reset is an option, that acts similar to power-on-reset, if enabled. Most HDL designs have a user defined reset in the code, it can be triggered from any pin of your choice. Unused pins should have their weak-pullup resistor enabled to avoid increased device supplied current possibly caused by floating inputs. It's a global device option, that can be set for all unused pins.

    --- Quote End ---

    i am sorry, maybe I did not give a precise description of the problem,these are two user defined reset pins in my design,which will reset all registers when they becomes low,and the global pin can give the smallest delay,so i want to use global pins to achieve my requirement，so may i use the global oe pin as the global reset pin?

    thanks very much!
  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    Doesn't the global oe pin just tristate all the user I/O? Mainly used for ICT?

    I would think it would be better to put this signal on one of the dedicated global inputs.
  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    Unlike global reset, global OE isn't said to have dedicated routing resources. Thus a GCLK input would be the preferred source to minimize routing effort with your second reset input. I don't expect timing issues with a global reset, normally. If unrelated to the system clock, it should be synchronized for safe reset behaviour anyway (a feature, that can't be achieved with the dedicated global reset input, by the way).

  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    --- Quote Start ---

    Unlike global reset, global OE isn't said to have dedicated routing resources. Thus a GCLK input would be the preferred source to minimize routing effort with your second reset input. I don't expect timing issues with a global reset, normally. If unrelated to the system clock, it should be synchronized for safe reset behaviour anyway (a feature, that can't be achieved with the dedicated global reset input, by the way).

    --- Quote End ---

    nice job,thank you very much!