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Old 05-28-2007, 06:32 PM
Posts: n/a
Default Re: M-RAM allocation in Stratix EPS125B672C6

On May 23, 12:07 am, [email protected] wrote:
> Hi ,
> I am using Altera Quartus II version 4.0 . The EPS125 device has
> 138 M4K blocks
> 224 M512 blocks
> 2 number of 512K Mram blocks
> has a total of 1,944,576 bits.
> (
> trimatrix.html )
> the problem i am facing is i am trying to fit in 4 buffer data blocks
> each of size 16384*14 bits
> (total 229376*4 =917504)
> plus i have additional fifo and single port Ram of sizes 8192 , and
> 1500 bits
> The problem is though there is adequate RAM available , I am not able
> to fit in all the memory; only 48% of the RAM is used.
> The fitter resourse summary says more M-Ram blocks are required but
> most of M4K and M512 blokcs are not used. ie 40/224 M512 blocks are
> used, 2/138 M4K blocks and 2-MRam blocks...
> I am fairly new to FPGAs and stuff so i would appreciate all help.
> thanks and regards.


It does appear you have enough RAM in the device. You should put 2 of
your buffer data blocks in M-RAMs (one M-RAM for each), and two more
in M4K RAMs (56 M4Ks for each). The remaining RAMs look to be small
and appear to be fitting fine.

You have two options to make this happen.

1. In the altsyncram megafunction, choose the type of the memory
block to be M4K for two of the buffers. The other two should use a
different altsyncram instantitation that either leaves RAM type set to
Auto, or chooses M-RAM.

2. Upgrade to a more recent version of Quartus II. I believe that
the latest versions of Quartus II will automatically figure out that
you don't have enough M-RAMs to implement all four of these data
buffers, and will move two of them to use M4Ks, when you leave the RAM
type set to Auto (the default).

Hope this helps.

Vaughn Betz

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