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VERILOG and VHDL

Discussion in 'Electronic Design' started by [email protected], Aug 26, 2006.

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  1. Guest

    could someone pls tell me books which i could follow to implement
    projects on FPGA or CPLD using XILINX or ALTERA.How much does an altera
    or xilinx complete kit cost in INDIA.
     
  2. PeteS

    PeteS Guest

    My favourite book that covers both Verilog and VHDL is 'HDL Chip
    Design' by Douglas J. Smith.

    You'll have to contact the Xilinx or Altera people for the cost of a
    dev kit where you are.

    The design flows in the Altera and Xilinx tools are somewhat different,
    but independent of the HDL language used. You can get the development
    environment (mostly) free on the web from both vendors.

    Cheers

    PeteS
     
  3. Slurp

    Slurp Guest

    You do not need to know Verilog or VHDL or indeed any other textual HDL to
    implement designs in FPGA's or CPLD's.

    Personally I find they get in the way of producing high speed complex bug
    free designs.

    I design highly complex image processing/camera/video systems using nothing
    more than schematic capture and a hierarchical design structure.

    This provides designs that are highly modular, self documenting and easily
    understood and modified years later by other engineers.

    Slurp
     
  4. Nico Coesel

    Nico Coesel Guest

    Depends on what you are designing. Complex logic is terrible to
    maintain when contained in a schematic. The same goes for showing the
    design hierarchical overview in HDL. My designs are mostly hybrid.
    Schematics to connect the blocks and do simple counter / buffer stuff,
    HDL for complex statemachines. And some documentation ofcourse.
     
  5. Guest

     
  6. Guest

     
  7. krw

    krw Guest

    Nonsense. VHDL and Verilog are used industry wide for such things.
    Apparently it's only you who has this problem.
    ....and you can't do this in a HDL? At one time I thought like you,
    but then I grew up. Schematics might be great for dataflow and
    analog circuits, but they suck for any complex logic.
    Nonsense again. VHDL is quite easy to make self-documenting. My
    guess is that you've never really tried to change tools. I have,
    and I'll not go back, willingly.
     
  8. Slurp

    Slurp Guest

    Nowhere did I say VHDL and Verilog is not the norm - just that it really is
    not necessary if you know what you are doing and want to get the job done.
    I don't consider I have a problem at all, I can get to a solution before
    anyone else using a HDL.


    Didn't say I couldn't ( you seem to be very defensive!) . I can write
    Verilog - does not get to the solution very quick, easy to intoduce bugs and
    very hard to find your way round hundreds of pages of script.
    A picture is worth a thousand words. If you create or use megafunctions you
    really do not need to be involved with gate level logic - I guess graphical
    languages have moved on since you last looked!
    Horses for courses - you carry on your way and I will carry on mine - I
    certainly don't have a problem with that.



    Slurp
     
  9. krw

    krw Guest

    You must do some pretty simple stuff. Try designing a processor
    using only schematics. It was done thirty years ago. It is no
    longer. I wonder why?
    Defensive, nope. I'm on the offense. Defense is for wussies. ;-)
    You must be very poor at it.
    Nope. A well done hierarchical design in a HDL is quite easy to
    read. Complex state machines are a piece of cake.
    I think you're shortchanging yourself. Like I said, I once
    resisted VHDL (and even had another engineer do the designs from my
    specs). No longer.
     
  10. Slurp

    Slurp Guest

    One module (out of around 68) of a recent Altera Stratix II design was a 32
    bit RISC processor designed from scratch and verified in less than 2 weeks.
    The compiler took another 2 weeks to write.
    All designed using hierarchical schematics. The whole project has taken me
    single handed less than 6 months.

    If that is simple stuff then I take my hat off to you.
    On the contrary.

    ...... as are they using a graphical approach.
    Experiance and results say not.
     
  11. PeteS

    PeteS Guest

    I expected a Holy War [tm], but not necessarily over the schematic/HDL
    issue ;)

    FWIW, when I do FPGAs, I do them exclusively in HDL. I personally find
    it much simpler to deal with than a schematic, although I am perfectly
    at home in schematics (I had better be ;)

    I had quite a learning curve to get to this, but once I got comfortable
    with HDL [some years ago now] , I personally won't look back - a
    description of a part in Verilog or VHDL tells me more (imo) about the
    part than any pure schematic symbol ever could. Interestingly, one of
    the reasons I started learning HDL was because I had to write some
    programs to implement a bunch of boundary scan tests, and BSDL is a
    subset of VHDL. I chose to learn BSDL as it is integral to really
    understanding JTAG tests.

    There are those who see it differently, of course.

    Cheers

    PeteS
     
  12. John  Larkin

    John Larkin Guest

    I agree, but we are in the minority. I find that my schematic-based
    designs are simpler, faster, and far less prone to bugs as compared to
    things that HDL designers do. HDLs are good for some things like
    tables and address decoders, just wrapped in a box and properly
    commented.

    I greatly prefer flipping through, say, 30 pages of nicely commented
    schematics as compared to, say, 5000 lines of cryptic, uncommented
    VHDL.

    All my FPGA schematics begin with a block diagram, a table of
    contents, and timing diagrams.

    John
     
  13. Slurp

    Slurp Guest


    Eureka! - A like minded professional at last!
    As you say John, we are very much in the minority!

    May be it is just the way our brains are wired.

    Slurp
     
  14. Joel Kolstad

    Joel Kolstad Guest

    OK; hopefully you realize this is not true for everyone.
    All the contemporary Verilog/VHDL "suites" (e.g., ActiveHDL, ModelSim, etc.)
    support a mixed schematic entry/VHDL/Verilog design style. IMO, that is the
    best of both worlds... use an HDL for fancy behavioral logic like state
    machines, use schematics to visually "tie together" the various levels of
    the hierarchy... and then use whichever you prefer for the
    complex/high-speed parts.

    ---Joel
     
  15. Can you recommend an idiot level (me) schematic/fpga system, as I want
    to convert some ttl/cmos circuits to a single lump, memory address
    counters and glue logic etc.

    I've looked at the Xlinx site, and I couldnt even figure out what
    breed I wanted. I'm downloading one of their demos at the moment


    martin
     
  16. Slurp

    Slurp Guest

    If you download the Altera Quartus web edition from www.altera.com (you need
    to obtain a free license file) - one of the included libraries actually
    holds 74 series functions, eg in the schematic editor if you double click on
    the schematic page, enter "7490" or whatever - up pops the appropriate
    symbol and underlying logic. For more sophisticated counters (up to 256
    bits) enter "LPM_COUNTER" and you are presented with an easy to use
    multipage wizard to set up your counter configuration, and an appropriate
    symbol is dropped on the schematic when you finalize the wizard.

    HTH

    Slurp
     
  17. Wow, thanks for that, brilliant [insert ASCII for thumbs up here]


    martin
     
  18. Slurp

    Slurp Guest

    ...... forgot to add that for your application I recommend you look at the
    Altera MAX II range of CPLD's. A CPLD has on board non -volatile
    configuration memory which means the programmed device is 'stand alone' .

    If you use an FPGA you will need external NV memory - normally Flash, and
    some kind of boot loader. Altera do produce chips which have both the Flash
    and boot loader integrated in one device but these work out much more
    expensive than a 'roll your own' CPLD based loader and separate Flash.

    Another plus is that the CPLD's are much cheaper than an FPGA - a smallish
    MAX II part of the order £2 - £3 will typically hold the equivalent of
    50 - 75 MSI 74series logic functions with ease.

    Slurp
     
  19. John Larkin

    John Larkin Guest

    The Xilinx schematic library also has a lot of 74xx TTL blocks, plus a
    lot of general-purpose latches and counters and gates and stuff.

    You can grossly waste resources here, like using three outputs of a
    1:16 decoder, or five bits of an 8-bit latch; the compiler will strip
    out the stuff that's not actively used.

    John
     
  20. John Larkin

    John Larkin Guest

    Of course. Not everybody can produce high-speed, complex, bug-free
    designs.

    John
     
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