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Altera_Forum's avatar
Altera_Forum
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13 years ago

DE1 Board LED lighting up with no discernible reason

Hey guys, I'm very new to FPGA and the DE1 board, I got one yesterday to use in a digital logic class. I'm trying to learn and program on it, and for the most part it's going really well, but I'm having an odd problem. I'm using the switches, buttons, and green LEDs in my current project. It's working and doing what I want, but sometimes there is a red LED that lights up. In other projects, its been different red LEDs blinking at different intervals. I have checked and double checked, and there is no assignment to ANY red LEDs. Well, technically I have all 10 red LEDs in the assignment editor, but they are all disabled. Actually, I just checked to see if that was somehow the problem, so I deleted all the LEDR assignments and I still have the problem. Anyone know whats going on here?

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    13 years ago

    maybe it's an Unused Pins issue. Set them as input tri-stated(Assignments/Device/Device and Pin Options/Unused Pins).

  • Altera_Forum's avatar
    Altera_Forum
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    13 years ago

    Thanks, I think that fixed it! I was also wondering why the hex display showed "8888", but that looks like it was fixed with this too.

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    13 years ago

    By default, unused pins in the fpga are driven to output low during synthesis/pnr. The hex display in de1 is active low; thus all segments are lit up.