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Altera_Forum's avatar
Altera_Forum
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16 years ago

RAM Based Shift Register

Hi,

I'm working on a design that uses shift registers. I wish to map those registers to the memory bits of my Cyclone III FPGA. I used the MegaWizard Plug-in Manager to generate the RAM-based shift register. The problem is that my design requires the distance between taps to be one. Unfortunately, the minimum allowed tap distance is 3.

My question is: Is there a way that I can build my own custom shift register and tell Quartus to map it to the memory bits?

Thanks in advance,

A.AbdelFattah

1 Reply

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

    I don't see any resource advantage if you go to low values of tap distance.

    Remember the tap points have to be connected to read port of a ram. each ram has one read port. So for every tap point a block of ram is needed, these are then read in series.

    Having a tap per location implies one block per location and so you better off using registers in the first place.

    If your one tap distance is only needed at a localised point you may consider combining shift between registers and ram.