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From: Peter Alfke on 5 Mar 2010 12:13 On Mar 5, 8:08 am, Antti <antti.luk...(a)googlemail.com> wrote: > On Mar 5, 2:41 pm, Symon <symon_bre...(a)hotmail.com> wrote: > > > On 3/5/2010 11:39 AM, de4 wrote: > > > > Can someone show me an example of code in VHDL of simple state machine that > > > can be packed in to BRAM with any warnings, errors. I just worry that my > > > design won't work. I have ISE 11.1 and Spartan 3a... > > > XAPP291 > > xapp291 does NOT show how from SM VHDL code a implementation using > BRAM is generated by the tools > > Antti This is a very simple design, easily implemented in BRAM (if speed permits) You have 7 states, therefore you need 3 (encoded) outputs You have 6 incoming condition or jump codes. You use the BRAM as a synchronous look-up table, using as address the combination of any jump code with any state code. That means you need 9 inputs, and the BRAM is thus 512 x 3. ( "512 x 6" in your posting is nonsense) In hardware you must feed the three output bits back to the address inputs. You can use any additional otherwise unused outputs as decoded state descriptors, but that does not change the basic design. I suppose you know that the addressing information is automatically registered before it addresses the BRAM (which is really a BROM with fixed data content) Do not use any additional output pipelining, optionally available in some devices. Unfortunately I cannot give you any VHDL code, but the basic understanding should help you. I have described and promoted this type of design for many years. Peter Alfke, formerly Xilinx Applications (some of you may remember me)
From: glen herrmannsfeldt on 5 Mar 2010 14:10 Peter Alfke <alfke(a)sbcglobal.net> wrote: (snip) > Peter Alfke, formerly Xilinx Applications (some of you may remember me) and also notice that you don't post as often as before. I was not so long ago thinking of asking: There is picoblaze (8 bit), and microblaze (32 bit), but no nanoblaze (16 bit) or milliblaze (64 bit). It might even be interesting to have a femtoblaze (4 bit) processor. Maybe not so far off topic, as such processors are, at some level, complicated state machines. -- glen
From: Peter Alfke on 5 Mar 2010 16:19 On Mar 5, 11:10 am, glen herrmannsfeldt <g...(a)ugcs.caltech.edu> wrote: > Peter Alfke <al...(a)sbcglobal.net> wrote: > > (snip) > > > Peter Alfke, formerly Xilinx Applications (some of you may remember me) > > and also notice that you don't post as often as before. > > I was not so long ago thinking of asking: > > There is picoblaze (8 bit), and microblaze (32 bit), but no > nanoblaze (16 bit) or milliblaze (64 bit). It might even > be interesting to have a femtoblaze (4 bit) processor. > > Maybe not so far off topic, as such processors are, at some level, > complicated state machines. > > -- glen Blazes... "Picoblaze" was started by Ken Chapman (still at Xilinx UK) as a highly optimized design, an app note that works well with 4-input LUTs and BRAMs. Xilinx has unfortunately always treated it as an illiigitimate child. (NIH) It lives due to its efficiency, and due to Ken's competence, enthusiasm, and perseverance. "Microblaze" was started by Goran Bilski (originally in Sweden, and now, after some years in Calif., back again in Sweden.) It has always been treated as a legitimate Xilinx baby, and Goran has continuously improved it, and more designers are involved. It grew from 16 bits to 32 bits. Still a highly optimized design. I have no idea about plans for 64 bits. I visit the Xilinx cafeteria once every couple of months to chat with old friends. I did repeatedly offer my services as a consultant, even without pay, but there are no takers. Peter A.
From: whygee on 6 Mar 2010 04:59 Peter Alfke wrote: > I did repeatedly offer my services as a consultant, even without pay, > but there are no takers. Is it because of "budget restrictions" or because... you're outside the company's loop now ? are you an "outcast" already ? > Peter A. yg -- http://ygdes.com / http://yasep.org
From: Peter Alfke on 6 Mar 2010 13:36
On Mar 6, 1:59 am, whygee <y...(a)yg.yg> wrote: > Peter Alfke wrote: > > I did repeatedly offer my services as a consultant, even without pay, > > but there are no takers. > > Is it because of "budget restrictions" or because... > you're outside the company's loop now ? > are you an "outcast" already ? > > > Peter A. > > yg > > --http://ygdes.com/http://yasep.org All of it... But don't feel sorry for me, I am fine. Feel sorry for a company that is too hung up to take advantage of an available resource. Peter A |