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Altera_Forum's avatar
Altera_Forum
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11 years ago

Altmult_add and Almult_accum dsp ip cores blocks

Hello.

Using Quartus II 10.1 with Stratix IV GX.

I'm trying to use and make with the Megawizard, DSP block that can be an adder, subtractor, multiplier for two inputs of 18bit, and also I want to have the ability to have in it Saturation and Rounding which I can turn on or off in live..

I need the output to be 36 bit - I think it'll be enough, the numbers truly are max. 15bit long..

I'm trying to have this in the will it can be done within "Half_DSP" block...

I found it written several times in the Stratix IV Handbook and in the Arithmetic IPs User Guide: Looking in the output produed vhd files that were produced, I have no control signals or inputs to the module that I can turn on or off any of those abilities..

May I do or configure something wrong?

Thank you very much for helping it.

6 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    11 years ago

    --- Quote Start ---

    I want to have the ability to have in it Saturation and Rounding which I can turn on or off in live..

    --- Quote End ---

    For the given functionality, switch it from being "Enabled" to "Variable" and the input ports will be created.

    e.g. for ALTMULT_ACCUM Saturation, go to the Saturation tab in the wizard, change "Should saturation operation be performed at the output adder(s)?" from "Enabled" to "Variable".

    Then click the "More options.." button right below that to possibly configure additional settings for that port.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    11 years ago

    --- Quote Start ---

    For the given functionality, switch it from being "Enabled" to "Variable" and the input ports will be created.

    e.g. for ALTMULT_ACCUM Saturation, go to the Saturation tab in the wizard, change "Should saturation operation be performed at the output adder(s)?" from "Enabled" to "Variable".

    Then click the "More options.." button right below that to possibly configure additional settings for that port.

    --- Quote End ---

    Thank you so much. It was helpful!
  • Altera_Forum's avatar
    Altera_Forum
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    11 years ago

    A Continue.

    "I'm trying to have this in the will it can be done within "Half_DSP" block..."

    Now, with the updated generated block, I have the Rounding and Saturation enable\disable option.

    But,

    In the synthesis status, it seems that my altmult_add block needs 2x DSP units - according to the QuartusII Report..

    How can I drive it to be a "half_DSP" as it is declared in the Stratix IV GX Handbook?..

    Screen Captures of the Reports are attached.

    Thanks.
  • Altera_Forum's avatar
    Altera_Forum
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    11 years ago

    Stx IV half dsp block supports 18x18 but you have 4 inputs so you need two of these halves (which is why you got 2 of dsp 18x18)

  • Altera_Forum's avatar
    Altera_Forum
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    11 years ago

    you are right. 4 mults + adder needs half dsp block. So I only have to guess it could be your mode is not just that of 4 mult/add as you have accumulator. I am not sure about these blocks configurations exactly.

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    11 years ago

    --- Quote Start ---

    you are right. 4 mults + adder needs half dsp block. So I only have to guess it could be your mode is not just that of 4 mult/add as you have accumulator. I am not sure about these blocks configurations exactly.

    --- Quote End ---

    Thank you.

    I'll try to find out the reason..

    Lior.