Help with XILINX ISE VHDL.

Discussion in 'VHDL' started by GreenDay, May 12, 2009.

  1. GreenDay

    GreenDay

    Joined:
    May 12, 2009
    Messages:
    5
    Greetings:

    Im new on programming with VHDL, and I was wondering if someone can help me build a design a generic n-bit unit using VHDL and Xilinx ISE, that com-
    putes the derivative of a sequence of 2048 n-bit samples, and
    determines the last zero crossing point and the maximum of the
    derivative. Both values must be stored in registers, and a signal
    provided indicating they were found. The unit should at least
    have a input to enable operation, and an output to indicate that
    the sequence has been processed.

    I know that I need to create at least 3 registers(derivative,zero crossing point and maximum).

    If anyone could help me, I''ll really appreciate it.

    Thanks in advance.
     
    GreenDay, May 12, 2009
    #1
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  2. GreenDay

    JohnDuq

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    I suggest you spend $55.00 at DigiKey and buy a CoolRunner II Design kit (Digikey #DO-CPLD-DK-G). It gives you hardware to play with, and a good book to introduce you to writing VHDL and learning the ISE tool.

    After you go through that exercise you'll have a template to start your design.

    I also like the following sites for VHDL references:

    http://www.vhdl-online.de/tutorial/
    http://forums.xilinx.com/xlnx/
    http://www.eng.auburn.edu/department/ee/mgc/vhdl.html
    http://www.eda.org/comp.lang.vhdl/FAQ1.html

    John D
     
    JohnDuq, May 12, 2009
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  3. GreenDay

    GreenDay

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    May 12, 2009
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    John D:

    Thank you very much for the information. But if you or anyone else help me with that for example code structure or anything beside what you gave me.
     
    GreenDay, May 12, 2009
    #3
  4. GreenDay

    JohnDuq

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    ISE has templates available. Look for the light bulb labeled "Lanquage Templates".

    You can also search around the Xilinx site. Have fun learning VHDL!

    John D
     
    JohnDuq, May 12, 2009
    #4
  5. GreenDay

    GreenDay

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    Excellent just what im looking for. but John how do I get the DX/DY(Derivative) of a sequence of 2048N-bits?? how can I wrote that into Xilinx?? I have no idea how to create the derivative function. hope you can help me.
     
    GreenDay, May 12, 2009
    #5
  6. GreenDay

    JohnDuq

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    In the z-domain a derivative is simply the difference between adjacent samples, so you can set up something like this in a loop that passes through your data set:

    derivative <= sample(z) - sample(z-1);

    if (derivative > derivative_max) then
    derivative_max <= derivative;
    max_location <= z;
    end if;

    The nice thing about VHDL is you can simulate as much as you want until you get things figured out.

    Get a good digital control theory book (Discrete-Time Control Systems) for more theory there.

    John D
     
    JohnDuq, May 12, 2009
    #6
  7. GreenDay

    GreenDay

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    May 12, 2009
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    Thank you very much John. Great with that function I get the maximum point and Zero crossing point of my samples.

    I have to create a function that compares the different values and save it into a register right??? and then call the function that you already created.
     
    GreenDay, May 12, 2009
    #7
  8. GreenDay

    GreenDay

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    May 12, 2009
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    John or anyone else:

    How I create a subtract in VHDL no an adder/subtract. only the subtract???
     
    GreenDay, May 14, 2009
    #8
  9. GreenDay

    JohnDuq

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    JohnDuq, May 14, 2009
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