Clock signal remains HIGH forever in Spartan-3 Starter Kit from Digilent

Discussion in 'VHDL' started by Javi, Jul 25, 2006.

  1. Javi

    Javi Guest

    Hi,

    I have a problem with my Spartan-3 Starter Board from Digilent (FPGA
    xc3s400-5ft256). The clock (at pin T9) is always HIGH so the
    combinational logic works well but obviously the sequential logic
    doesn't work (flip-flops don't transition).

    The first thing I did when I bought the board was check it with s3demo
    and it worked fine, but later (I didn't change anything), after the
    first programing clycles the problem arose.

    The oscillator on the board (50MHz) works well, I think the problem is
    in the FPGA itself or with de tools (I use ISE 8.1i without Service
    Packs). Any idea?

    Sorry for my poor english.

    Thanks,
    Javi
    Javi, Jul 25, 2006
    #1
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  2. Javi schrieb:
    > The oscillator on the board (50MHz) works well, I think the problem is
    > in the FPGA itself or with de tools (I use ISE 8.1i without Service
    > Packs). Any idea?


    Check the pinout. Maybe your driving the pin as an output.

    bye Thomas
    Thomas Stanka, Jul 26, 2006
    #2
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  3. Javi

    Javi Guest

    Thanks Thomas.

    This is the reason. If use an IBUF component from Unisim Library
    (Xilinx) everithing works well (T9 pin is a input pin, not an output),
    but I never had the need to use this element before. Why now?

    Javi

    Thomas Stanka wrote:
    > Javi schrieb:
    > > The oscillator on the board (50MHz) works well, I think the problem is
    > > in the FPGA itself or with de tools (I use ISE 8.1i without Service
    > > Packs). Any idea?

    >
    > Check the pinout. Maybe your driving the pin as an output.
    >
    > bye Thomas
    Javi, Jul 26, 2006
    #3
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