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Altera_Forum
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16 years ago

Need help! Weird CycloneII LED assignment problem!

Hey guys,

My pins on board don't work as what they should do according to pin assignment.

In my design entity, I have outputs LEDR0, LEDR1... LEDR5. I assigned them to correct LED pins, nothing to the other LED pins. Then I configure the course code and the weird thing happens, LEDR7 is turned on. I have checked and there's definitely no assignment as LEDR7, and no such output, and nothing has been assigned to the pin where LEDR7 is.

Anyone can help me out of this?Anyone has a idea? Any suggestion is welcomed!

6 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    What's your device option for unused pins? It may be e.g. "output drinving ground". Apart from changing this option to "tristate with pull-up" you should generally define unused but connected pins in your design top and asign correct pins to them. It's meaningful in my opinion to have them ready for later use.

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    thank you for your reply first.

    My device option for unused pin is "output driving ground"

    Is it possible that the fitter randomly assign used pin to some pin?
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    "nothing has been assigned to the pin where LEDR7" would mean, that it should be set according to the unused pins default. I can't imagine a reason, why the fitter should assign anything different here, but you should check in the fitter pinout report. Personally I don't like the "driving ground" feature, because there's always a certain risk, that unused pins are connected different in the hardware design and could be possibly damaged in this case. But that's a different problem.

    Anyway, what happens, if you drive the R7 output explicitely to GND? I assumed first, that you are driving the LEDs active low, but understand, that they are active high, most likely you have a DE-2 board?
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Yes I have a DE-2. and LEDs are active high. I checked fitter pin out file, pin at location for R7 is set to GND. Since I actually don't have a pin as R7, I don't know how to drive it to GND......

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Strange indeed. Are you sure, that the pinout file refers to PIN_AC21? Is the LED also driven in other design or for an unconfigured FPGA? Sounds either like a hardware defect or a strange Quartus bug.

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    I'm using board EP2C20, the pin for LEDR7 is in fact PIN_U18, it was assigned not ground...to one of my output signal by quartus, I reassign it to ground and it works normal now.