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Getting started with FPGAs

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  • jmgjmg Posts: 15,169
    edited 2013-04-07 17:51
    graynomad wrote: »
    At present I am tossing up between CRII and Lattice MachX02, totally different beasts I know but they both have good features.

    The closest equivalent Lattice parts to the Xilinx XC2, are the Mach4000Z/4000 series.
    There is also the Atmel ATF15xx series, and Atmel also still make SPLDs.

    I did find that a test compile, targeting a Mach4256ZE, started to struggle as the part went over ~ 70% full.
    The Mach-XO2, seem to behave better as they pack toward 100%

    Here are some of my trial notes on increasing a width param, until it fails to fit in the LCMXO2-256HC target
    I think this was 2 Ctrs and 2 Capture/serialize of this width
    // parameter  CW = 47;	//   136 out of   128 (106%)  NO FIT @ 48b
    //parameter  CW = 43;	//   126/128    98% used
    //parameter  CW = 39;	//   115/128    89% used
     parameter  CW = 31;	//    93/128    72% used  
    // parameter  CW = 15;	//    51/128    39% used    
    
  • graynomadgraynomad Posts: 6
    edited 2013-04-08 09:26
    Thanks jmg, that gave me a better feel for what fits.

    We just spent hours discussing options and decided to go with the X02, or at least get the software and a dev board with a view to using it unless we find something we really hate.

    It's more than we need right now but I can see all sorts of stuff to do in future. One deciding factor was that when I downloaded a recent data sheet I discovered a "new" small package I was not aware of, a 32-pin QFN. The lack of a small hand-solderable package in the family was a big drawback I felt, problem solved with a new data sheet :)

    _____
    Rob
  • LeonLeon Posts: 7,620
    edited 2013-04-08 09:40
    I've always favoured the Altera CPLDs, as they are really small FPGAs.
  • jmgjmg Posts: 15,169
    edited 2013-04-08 16:45
    graynomad wrote: »
    ...when I downloaded a recent data sheet I discovered a "new" small package I was not aware of, a 32-pin QFN. The lack of a small hand-solderable package in the family was a big drawback I felt, problem solved with a new data sheet :)

    I forgot to mention the LCMXO2-256HC part above, was targeting the QFN32 package (hence the SPI readout)

    If you get a Breakout board, try to ensure it has the 7000 part, not the older stock 1200.
    Lattice say this

    Ordering Part Number: LCMXO2-7000HE-B-EVN

    Note: This replaces the LCMXO2-1200ZE-B-EVN. During the transition period, orders for the LCMXO2-1200ZE-B-EVN may be upgraded to the LCMXO2-7000HE-B-EVN. If you specifically require the LCMXO2-7000HE-B-EVN, it will be available on the Lattice on-line store in February 2013.



    Shame Lattice do not (yet?) have TQFP48, or even QFN48...
  • graynomadgraynomad Posts: 6
    edited 2013-04-09 08:46
    Yes I saw that message re the 1200/7000, I would certainly want the newer version.

    I'm trying the IDE now, we'll see how that goes before buying a board.

    I actually did an Altera chip maybe 20+ years ago, a PLCC68 package IIRC, real bleeding edge for us then.

    ______
    Rob
  • AleAle Posts: 2,363
    edited 2013-04-21 09:40
    Leon,

    The MachXO2 are in my opinion a bit better because they include block ram. That '1200 part has the same amount of logic as a 50 k gates FPGA.
  • AleAle Posts: 2,363
    edited 2013-04-21 09:40
    Leon,

    The MachXO2 are in my opinion a bit better because they include block ram. That '1200 part has the same amount of logic as a 50 k gates FPGA.
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