BRAM16 error
in [FPGA]
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From: Gabor on 20 Feb 2010 12:06 On Feb 19, 5:24 am, "bh.ines1...(a)gmail.com" <bh.ines1...(a)gmail.com> wrote: > On Feb 18, 7:48 pm, austin <aus...(a)xilinx.com> wrote: > > > Gabor, > > > Using BRAM blocks as 'look up tables' for logic is a way to pack more > > "stuff" into the design, so, yes, the BRAMs are only "unused" until > > you then use them for this purpose (the English language is probably > > one of the worst languages for describing technical stuff, except for > > all the others). > > > That is a fairly arcane use of the BRAM blocks, and it would be > > interesting to know how often folks do this, > > > Austin > > Hi, > Thank you (Austin and Gabor) for the answers. > But is this error caused by the fact that the application software is > big enough? I dont' think so cause the soft application is very > simple, it just light the 8 LEDs. > Also in the MHS file I put 16k for DLMB and 16k for the ILMB too! > So I couldn'tt understand where the problem lies: in the design in > hard or soft implementation!! > I will be thankfull if you give me some help!! > > Best Regards, > Ines Block RAMs on Spartan 3 are 18Kb where "b" means bits. For 16KB, where "B" means bytes, you need 8 BRAMs. Your memory for the MicroBlaze would therefore need 16 BRAMs. Add to that any additional BRAMs you might use, for example FIFO's and MIG cores. So the question is: How many BRAM devices does your FPGA have? How many BRAM's are shown in the Map report? How many BRAM's from the Map report are not accounted for? Regards, Gabor PS to Austin: Arcane or not, the tools are supposed to be able to use extra BRAM's for stuffing extra logic. I believe it is a bug if the tools overmap BRAM's when I have no means to tell the tools how many of the BRAM's it can use for logic. It doesn't seem like rocket science for the tools to first allow for any explicitly required BRAM's in the design before mapping logic into the remaining "unused" ones.
From: Anssi Saari on 21 Feb 2010 07:37
Gabor <gabor(a)alacron.com> writes: > How many BRAM devices does your FPGA have? That's easy to answer, the Spartan3 starter the OP mentioned has a XC3S200, so 12 BRAMs. Not quite enough for 32 kB. The answer to the original poster is, create your MicroBlaze design in the EDK using the wizard and leave all settings at their defaults. You'll get a system that actually *works* and you can play with. |