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Altera_Forum's avatar
Altera_Forum
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18 years ago

evaluating ressources saving between differents families

Hi!

I'm trying to evaluate the amount of logic cells used for different standard operations (like addition, multiplication..) for differents Altera devices.

I particurlarly want to know the gain between using a Stratix device with the embedded multiplier for a multiplication operation (8*8 bit for example) rather than a Cyclone device for example. The problem is that I have no idea of the amount of logic cells used for an embedded multiplier!

I also want to compare the stratix and stratix 2 device. But the first one has LE units for the elementary block and the second one has ALM unit. How can I get some relevant information of this?

Can somebody help me?

Regards

5 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    18 years ago

    One (obvious) method could be to make some test designs in Quartus and compare. If you know quartus, its simple and its easy to swicth target. If you dont have Quartus you can download web edition for free, but you will of course have to spend time learning to use it!

    Just had a quick look in megawizard and that says

    Resource result is for 8x8 mult

    Cyclone: 117Lut's

    Cyclone II, III: 1 Dsp-9bit block

    Stratix " ", II, III: 1 Dsp-9bit block

    Resource result is for 16x16 mult

    Cyclone: 357Lut's

    Cyclone II, III: 2 Dsp-9bit block

    Stratix " ", II, III: 2 Dsp-9bit block

    Resource result is for 32x32 mult

    Cyclone: 1221Lut's

    Cyclone II, III: 8 Dsp-9bit block+110Lut's

    Stratix " ", II, III: 8 Dsp-9bit block
  • Altera_Forum's avatar
    Altera_Forum
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    18 years ago

    Even the Megawizard usually shows the sizes, and I believe the user guides do to. They're not always 100% accurate, but pretty close. (The user guide charts can't show every option, so they're based off specific settings. The Megawizard usually shows guesstimates in the lower left corner, but since it hasn't actually gone through synthesis, there's no way to know for sure.) In the end when evaluating size and/or performance, designers have a bunch of test projects that they throw something into and give a quick run. I still do schematics for this, and probably end up making a new one every other week to see something else. (If you have a lot of multiplier requirements, you're going to see significant area savings in the DSP blocks...) But shouldn't you be targetins Cyclone III, which has DSP blocks in it too, or is this an older board you have?

  • Altera_Forum's avatar
    Altera_Forum
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    18 years ago

    I have tried to compare some design tests in Quartus. But maybe it is simple and faster with the megawizard.

    I'm not targeting Cyclone III because I don't have any board of them. So it's not useful for me at the moment.

    I need also to compare things like case, if.. elsif... and others.

    But my main problem is, is it relevant to compare different families if they do not have the same elementary element.

    For example, LEs for Stratix, ALM for StratixII, CLB for Spartan etc...
  • Altera_Forum's avatar
    Altera_Forum
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    18 years ago

    Hi,

    in the Stratix2 Handbook, there is a table where the ALMs and the Equivalent LEs are shown. Between the two values there is a constant factor of 2.5. This value can be used as reference value.

    Of course the exact calculation depends on the design. E.g. large multiplexers can be realized in a better way in a Stratix II because of the possibilities to use the LUT as Six-Input LUT.

    On the other side, in Stratix devices each LE keeps a register. In Stratix II devices the number of equivalent LEs is not the number of registers. (Each ALM keeps two Registers)

    So each device/vendor has different strengths and it depends on the design how much ressources are needed. (e. g. the DSP blocks from Altera and Xilinx are different and can make timing problems when porting designs from one vendor to the other one)
  • Altera_Forum's avatar
    Altera_Forum
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    18 years ago

    Hi,

    If you really want to know the logical cells you used,Quartus may be your better choise！

    The megawizard is something you should consider too.

    It's not difficulty!