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Messages from 117575

Article: 117575
Subject: Re: Help with a face recognition system
From: Jan Panteltje <pNaonStpealmtje@yahoo.com>
Date: Wed, 04 Apr 2007 13:49:01 GMT
Links: << >>  << T >>  << A >>
On a sunny day (4 Apr 2007 05:43:42 -0700) it happened "Patrick Dubois"
<prdubois@gmail.com> wrote in
<1175690622.594433.213100@d57g2000hsg.googlegroups.com>:

>On Apr 3, 2:00 pm, Jan Panteltje <pNaonStpealm...@yahoo.com> wrote:
>> On a sunny day (3 Apr 2007 08:21:24 -0700) it happened "PatrickDubois"
>> <prdub...@gmail.com> wrote in
>> <1175613684.443163.290...@d57g2000hsg.googlegroups.com>:
>>
>> >On Apr 3, 8:59 am, Jan Panteltje <pNaonStpealm...@yahoo.com> wrote:
>> >> PS3 has only 1 power processor and _6_ SPE cores.
>> >>  http://en.wikipedia.org/wiki/PlayStation_3#Central_processing_unit
>>
>> >Nope, 1 central PPC core and 8 Synergistic Processor Unit:
>> >http://www.research.ibm.com/cell/heterogeneousCMP.html
>>
>> Nope, in the PS3 only 6 are available.
>
>Alright, I don't want to argue about this but I think we can fairly
>say that the info on the web is not clear...
>Just for fun, here's a link directly from Sony with the PS3 Cell
>specs :)
>http://cell.scei.co.jp/index_e.html

OK, all good and well, but here some facts:
 PS3 runs Linux in a 'hypervisor'.
The hypervisor limits access to whatever Sony pleases to allow access too.
One SPE is in use for the PS3 graphics, and no way you can touch it from Linux.
The story goes IMB had yield problems, so Sony settled for chips with one
working core less.
That leaves 6 available from Linux.
The wikipedia article is up to date and quite correct.
Version of Linux that runs on PS3: Yellow dog Linux.
If you are in Europe, there is a special C'T magazine release out with YD Linux for PS3
including some of the IBM development tools:
 https://www.heise.de/kiosk/special/ct/07/01/

All I can tell you now.


Article: 117576
Subject: Re: Help with a face recognition system
From: "Patrick Dubois" <prdubois@gmail.com>
Date: 4 Apr 2007 07:15:35 -0700
Links: << >>  << T >>  << A >>
On Apr 4, 9:49 am, Jan Panteltje <pNaonStpealm...@yahoo.com> wrote:
> On a sunny day (4 Apr 2007 05:43:42 -0700) it happened "Patrick Dubois"
> <prdub...@gmail.com> wrote in
> <1175690622.594433.213...@d57g2000hsg.googlegroups.com>:
>
>
>
> >On Apr 3, 2:00 pm, Jan Panteltje <pNaonStpealm...@yahoo.com> wrote:
> >> On a sunny day (3 Apr 2007 08:21:24 -0700) it happened "PatrickDubois"
> >> <prdub...@gmail.com> wrote in
> >> <1175613684.443163.290...@d57g2000hsg.googlegroups.com>:
>
> >> >On Apr 3, 8:59 am, Jan Panteltje <pNaonStpealm...@yahoo.com> wrote:
> >> >> PS3 has only 1 power processor and _6_ SPE cores.
> >> >>  http://en.wikipedia.org/wiki/PlayStation_3#Central_processing_unit
>
> >> >Nope, 1 central PPC core and 8 Synergistic Processor Unit:
> >> >http://www.research.ibm.com/cell/heterogeneousCMP.html
>
> >> Nope, in the PS3 only 6 are available.
>
> >Alright, I don't want to argue about this but I think we can fairly
> >say that the info on the web is not clear...
> >Just for fun, here's a link directly from Sony with the PS3 Cell
> >specs :)
> >http://cell.scei.co.jp/index_e.html
>
> OK, all good and well, but here some facts:
>  PS3 runs Linux in a 'hypervisor'.
> The hypervisor limits access to whatever Sony pleases to allow access too.
> One SPE is in use for the PS3 graphics, and no way you can touch it from Linux.
> The story goes IMB had yield problems, so Sony settled for chips with one
> working core less.
> That leaves 6 available from Linux.
> The wikipedia article is up to date and quite correct.
> Version of Linux that runs on PS3: Yellow dog Linux.
> If you are in Europe, there is a special C'T magazine release out with YD Linux for PS3
> including some of the IBM development tools:
>  https://www.heise.de/kiosk/special/ct/07/01/
>
> All I can tell you now.


Ok, thanks for the clarification.


Article: 117577
Subject: Re: high number of multipliers / low cost
From: ryan_usenet@yahoo.com
Date: 4 Apr 2007 07:28:58 -0700
Links: << >>  << T >>  << A >>
Thank you for your replies so far.

It is no problem if the chip is ~1000$, because the aim is some 10^12
multiplications/s. The simplistic estimate needs 3 chips V5 SX95T or
27 chips EP2C70. For easier design a lower number of chips is
preferred.

Is there some more comprehensive overview of FPGA prizes, especially
for the larger devices, than what I find at www.digikey.com?

Although your suggestions have already been useful, I'd appreciate
more hints maybe concerning exotic manufacturers that I have never
heard of. Or are Xilinx and Altera definitely the only choices?

Best regards,
Ryan

(
>Wow, FPGA marketing departments are going to be swarming all over you like
>it's Christmas!
>
>Wait, are you sure you're real...? ;-)
>
>    -Ben-
Why do you doubt this? Because the question sounds stupid? I don't
pretend that I am close to production of the planned FPGA board, but I
need an idea of what will be possible at what costs.)


Article: 117578
Subject: fifo occupancy bigger than fifo size?
From: "cpope" <cepope@nc.rr.com>
Date: Wed, 4 Apr 2007 10:54:51 -0400
Links: << >>  << T >>  << A >>
Note: using EDk 8.2.02 with peripheral generated with the wizard with FIFO
enabled and one user interrupt that is set to the fifo_almostfull line.

I'm set up to generate interrupts on the fifo almost full signal but I get a
couple interrupts and then it stops. If I go read the occupancy register I
get a number(0x737) greater than the size of the fifo (0x400). If I then go
and manually read from the fifo data register(from gdb) I can get the
occupancy to go back to 0x400 and the next interrupt occurs when I run but
they stop shortly after.

So,
How could the occupancy be greater than the size of the fifo?
Have you seen anything like this before?

Thanks,
Clark



Article: 117579
Subject: Re: high number of multipliers / low cost
From: "Symon" <symon_brewer@hotmail.com>
Date: Wed, 4 Apr 2007 16:22:27 +0100
Links: << >>  << T >>  << A >>
<ryan_usenet@yahoo.com> wrote in message 
news:1175696938.323383.273760@o5g2000hsb.googlegroups.com...
>
> Although your suggestions have already been useful, I'd appreciate
> more hints maybe concerning exotic manufacturers that I have never
> heard of. Or are Xilinx and Altera definitely the only choices?
>
> Best regards,
> Ryan
>
Hi Ryan,
Don't forget FPGAs have other resources apart from 'hard' multipliers. Check 
this page on Mr. Andraka'a website about distributed arithmetic. You can 
make a _lot_ of multipliers out of the ordinary fabric of FPGAs.
HTH, Syms.

http://www.andraka.com/distribu.htm 



Article: 117580
Subject: TFP410 acceptable video input timings (trying to run 1280x1024 at 60Hz with clock slower than 108 MHz)
From: "wallge" <wallge@gmail.com>
Date: 4 Apr 2007 08:28:59 -0700
Links: << >>  << T >>  << A >>
I am trying to get video through an fpga to a texas instruments TMDS
transmitter chip (TFP410).
I would like see video out at 1280x1024 at 60 FPS. The VESA spec calls
for this to be clocked at
108 Mhz. But if you look at the actual amount of data (1280x1024x60 =
78.6 MHz)
108 Mhz is alot of overhead for the actual number of valid pixels that
need to be pushed
through the system.

The FPGA I am using (a stratix I) doesn't want to run this fast.
I would like to generate my video at a slower clock speed (with less
blanking time).
Does anyone know if the TFP410 will accept input video with less
blanking time than
the VESA spec allows for?

I have been experimenting with slower clock rates but can't seem to
get them to work
with the blanking intervals / timing parameters i have chosen.

I wondered if there was some formula that I needed to follow.

I have asked TI about this and they have been unhelpful.


Article: 117581
Subject: Re: high number of multipliers / low cost
From: Austin Lesea <austin@xilinx.com>
Date: Wed, 04 Apr 2007 08:35:08 -0700
Links: << >>  << T >>  << A >>
Ryan,

Your metric is extremely simple.  Perhaps too simple?  What is it that
you wish to do?  1E12 multiplies per second is a bit too simplistic.

You need to consider the 'care and feeding' of this 'monster'.

What is the resolution required? 18X18? or 9X9? Or really 25 X 18?

Is it all multiplies, and no accumulates?  Hard to imagine a problem
where no addition whatsoever is required.  Multipliers alone may not
suffice.  What about accumulators?  What number of bits?  The DSP48
blocks in the Xilinx architectures are intended for most common needs.
The DSP48 in V5 also has the traditional 4 bit control (16 function) ALU
as part of the DSP block.  Very wide AND, OR, XOR, etc. are all provided.

You should also consider how much SRAM is on chip.  If you have
insufficient RAM, you can not "feed your monster."

Similarly, IO is required to feed the RAM, and get the results.  You
need to consider if the IO is a bottleneck (limits your performance).

Austin

Article: 117582
Subject: Re: high number of multipliers / low cost
From: ryan_usenet@yahoo.com
Date: 4 Apr 2007 08:40:34 -0700
Links: << >>  << T >>  << A >>
On 4 Apr., 17:22, "Symon" <symon_bre...@hotmail.com> wrote:

> Hi Ryan,
> Don't forget FPGAs have other resources apart from 'hard' multipliers.

Well part of the other logic is of course needed for accumulation,
registers etc. If huge amounts of logic will be free, my plan is to
use those as additional 'software' multipliers.

However, I have no idea how efficient these multipliers built from
logic blocks can be. As far as I know you have the choice of
implementing either parallel or sequential 'software' multipliers. The
parallel architecture has the advantage that it can calculate 1
product per clock, but requires lots of logic, so that not many of
them could be used. The sequential architecture needs about 1/nth of
the logic space, but finishes after about n clocks, so that I don't
expect either of these solutions to significantly contribute to the
dedicated 'hardware' multipliers performance.

If the sequential multiplier could be used in 'pipeline' operation
(meaning the result is delayed by n clocks, but then a new result is
produce in each cycle), this would be interesting, but I guess, it
cannot?

Thanks
Ryan


Article: 117583
Subject: Re: TFP410 acceptable video input timings (trying to run 1280x1024 at 60Hz with clock slower than 108 MHz)
From: "Ben Jones" <ben.jones@xilinx.com>
Date: Wed, 4 Apr 2007 16:42:08 +0100
Links: << >>  << T >>  << A >>

"wallge" <wallge@gmail.com> wrote in message 
news:1175700538.999587.321180@d57g2000hsg.googlegroups.com...
>I am trying to get video through an fpga to a texas instruments TMDS
> transmitter chip (TFP410).
> I would like see video out at 1280x1024 at 60 FPS. The VESA spec calls
> for this to be clocked at
> 108 Mhz.
> The FPGA I am using (a stratix I) doesn't want to run this fast.

The FPGA will run plenty fast, but you probably need to fix your design if 
it doesn't meet your timing requirements.

> Does anyone know if the TFP410 will accept input video with less
> blanking time than the VESA spec allows for?

You cannae change the laws of physics. The DVI transmitter might be capable 
of transmitting with near-zero blanking but the monitor at the other end 
will have none of it. In order to compress the data stream coming out of 
your hypothetical slowed-down video source into a pixel stream at a 108MHz 
dot clock, something somewhere is going to have to buffer a whole lot of 
video data to effect the rate change. The best candidate for that 
"something" is really the FPGA you're designing.

> I wondered if there was some formula that I needed to follow.

Google for VESA GTF (General Timing Formula).

    -Ben- 



Article: 117584
Subject: Re: high number of multipliers / low cost
From: "John_H" <newsgroup@johnhandwork.com>
Date: Wed, 4 Apr 2007 08:52:47 -0700
Links: << >>  << T >>  << A >>
<ryan_usenet@yahoo.com> wrote in message 
news:1175686533.726030.62610@d57g2000hsg.googlegroups.com...
> Hello,
> I need the highest possible number of multiplication operations per
> second at low cost. I know that several factors affect the overall
> performance, but since I have no idea which FPGA chips might be worth
> to be considered, I'd like to ask what you think is the chip with the
> lowest ratio
>
> R=(price of chip)* (delay time)/(number of multipliers)
>
> 18x18bit multipliers seem to be quite common, so lets assume this
> design for the estimate.
>
> For example for the Spartan XC3S1000 (~60$, 24 multipliers, 4ns delay)
> I have
> R= 10$ per (Billion multiplications/s). The Cyclone EP2C70 (~230$, 150
> multipliers, 4ns delay) has R=6.13$ per (Billion multiplications/s).
>
> Do other FPGAs exist that are maybe specialized for multiplication-
> intensive tasks and which therefore are much cheaper?
>
> Best regards,
> Ryan

Another chip to consider: the Lattice ECP2(M) series.

The Lattice approach was to stuff the inexpensive chips with DSP resources 
since many massively parallel algorithms can't afford the super-performance 
chips.  Their sysDSP blocks can be configured for 8x9-bit, 4x18-bit or 
1x36-bit multipliers per block.  A MAC structure is included for FIR style 
applications.  For 18-bit multipliers, an 88 multiplier solution has a 
"marketing" price around $35 (ECP2-70).  I think your 18-bit R value is 
about $1.60 but I have a little difficulty figuring out the multiplier 
speeds.

The families with the most multipliers at reasonable costs - Altera Cyclone 
III, Xilinx Spartan-3DSP, Lattice ECP2 - are all rather new.  The costs 
might be larger in the near term than marketing announcements would suggest. 
You really need to get conversations going with the sales reps from these 
three companies so that they can work the numbers toward your goal.  Getting 
them to where they can understand your pipeline needs, they should be able 
to give you a true attainable frequency and a price or price range that 
would allow you to compare to your economy of scale.

Something else that might interest you is the FPOA from Mathstar.  Their 
"Field Programmable Object Array" has MACs, ALUs, and Register Files as the 
distributed elements capable of 1 GHz speeds according to their literature. 
Since this product is far outside my tecnical needs, I haven't delved too 
far into it but your application might be one of the few FPGA-style designs 
that can seriously leverage this not-so-mainstream technology.







Article: 117585
Subject: Digital Receiver chip suggestion
From: "morpheus" <saurster@gmail.com>
Date: 4 Apr 2007 09:06:11 -0700
Links: << >>  << T >>  << A >>
Hi Folks,
I've been active on this forum asking questions on digital receiver.
Earlier I was doing most of the work in the FPGA (thats how I
architected it). Due to space constraints, this radio is going to be
used as a Search and Rescue radio for the coast guard, I am re-
architecting and planning to use a multi-channel  digital receiver
chip instead. This helps us to get rid of most of our analog front end
and do minimal processing in the FPGA, and thus use a smaller FPGA
also.
The chips that come to mind are AD6654 and AD6624A. The AD6654A is
special as it has the in-built ADC.
Now some specs on my design requirements
a) 4 channels,
b) 121.5MHz - 245MHz band of interest.
c) AM, FM, FSK demodulation.
I have also looked at some Grayscale chips. I was wondering if you
have any more suggestions.
Thanks
Morpheus


Article: 117586
Subject: Re: high number of multipliers / low cost
From: "Ben Jones" <ben.jones@xilinx.com>
Date: Wed, 4 Apr 2007 17:11:57 +0100
Links: << >>  << T >>  << A >>

<ryan_usenet@yahoo.com> wrote in message 
news:1175701234.081630.27560@d57g2000hsg.googlegroups.com...
> On 4 Apr., 17:22, "Symon" <symon_bre...@hotmail.com> wrote:
>
> As far as I know you have the choice of
> implementing either parallel or sequential 'software' multipliers. The
> parallel architecture has the advantage that it can calculate 1
> product per clock, but requires lots of logic, so that not many of
> them could be used.

You would have to define "lots". Also, you might calculate one product per 
clock with a fabric-based multiplier, but it will be a pretty long clock 
cycle.

> If the sequential multiplier could be used in 'pipeline' operation
> (meaning the result is delayed by n clocks, but then a new result is
> produce in each cycle), this would be interesting, but I guess, it
> cannot?

No, but the "parallel" multiplier architecture could. Indeed, it must be, or 
your clock speed would be ridiculously slow.

It would be interesting to know what you think "a multiplier" is - i.e. what 
word-length, and are you talking about fixed-point or floating-point 
operations?

    -Ben- 



Article: 117587
Subject: Re: Does the XC3S250E-VQ100 exist?
From: "radarman" <jshamlet@gmail.com>
Date: 4 Apr 2007 09:19:58 -0700
Links: << >>  << T >>  << A >>
On Apr 3, 8:12 am, "Paul" <pauljbenn...@gmail.com> wrote:
> Yea... for non-BGA packages - Altera seems to give you more logic.
>
> If you're really stuck on Xilinx, I'd pick up the phone and call Avnet
> (or whoever
> their equivalent is if you're not in the US) to find out what's
> actually available.
> Often, all the configurations listed aren't actually produced unless
> they have
> orders for them.
>
> If you're not stuck on Xilinx - look into Altera.  And don't limit
> yourself,
> check out the smaller guys too - lattice semiconductor has a pretty
> decent non-BGA offering as well.
>
> On Apr 2, 6:26 pm, "John_H" <newsgr...@johnhandwork.com> wrote:
>
> > "radarman" <jsham...@gmail.com> wrote in message
>
> >news:1175547385.428898.143910@o5g2000hsb.googlegroups.com...
>
> > >I have an application that is very space limited, and would like to
> > > use a Spartan XC3S250E in the VQ100 package. Even this package has
> > > more I/O than I need. (I need a lot of logic, but communication is via
> > > SPI and RS232 - about 10 I/O total)
>
> > > I can find the 3S100E's in this package from most distributors, but
> > > not the 3S250E.
>
> > > I only need four total, and I could probably squeeze a TQ144 package
> > > in if I got creative with parts placement, but the PQ208 absolutely
> > > won't fit.
>
> > > Also, since these are prototypes, I would like avoid BGA's. The cost
> > > to have them fitted is just too high.
>
> > > BTW - if anyone from Xilinx is reading this, this is why it would be
> > > nice if your online store was actually a "store", and not just a link
> > > to Avnet and Nu Horizons.
>
> > > Thanks!
>
> > This is where a distributor/sales contact (distributor FAE, for instance)
> > can really help out.  Even if you're "small potatoes" for their business,
> > they should be able to tell you about availability.  The online store
> > *would* be a tremendous resource if it was in a usable state.- Hide quoted text -
>
> > - Show quoted text -

Without the VQ100 package, Altera does appear to be the better chip at
this end of the spectrum. Not only does it have more equivalent gates,
but if I'm reading the datasheet right, it only needs two supply
voltages - 3.3v and 1.2v. That will cut an extra switcher from the
board, which somewhat makes up for the larger package.

Plus, Digikey is carrying both the 2c5 and 2c8 in the TQ144 package in
stock.


Article: 117588
Subject: Re: Looking for Memory Recommendation for Spartan 3E 1200
From: nico@puntnl.niks (Nico Coesel)
Date: Wed, 04 Apr 2007 16:22:48 GMT
Links: << >>  << T >>  << A >>
Matthias Einwag <matthias.einwag@web.de> wrote:

>Hi everyone,
>
>I'm working on a Board for Bus Interfacing and some Audio Processing, 
>which will use Spartan 3E 1200 and the Microblaze.
>Now I'm not sure what kind of memory I should use. Size ist not too 
>important for me. 8Mbytes would be ok, but more is always better. But 
>the speed should be high enough to get the Microblaze run at a decent 
>speed and to allow permanent storing auf 4 stereo audio streams.
>Most important is, that the layout and memory interface should run 
>stable and from the beginning. There's not much time for error 
>investigations and redesigns.

Your bandwidth requirement is less than 800kB/s. How about compact
flash or an SD-card? These are well known and there are loads of
resources available on the internet. 

>Spartan 3E Starter Kit uses a 16bit Wide DDR SDRAM Memory. But I read 
>here and in some other boards, that people have much trouble with this 
>one. Is this because Spartan 3E and the given IP Cores have always 
>Trouble with DDR, or because of the missing clock feedback path on the 
>board?

There are no free _usefull_ cores to control DDR memory. 

-- 
Reply to nico@nctdevpuntnl (punt=.)
Bedrijven en winkels vindt U op www.adresboekje.nl

Article: 117589
Subject: Re: high number of multipliers / low cost
From: ryan_usenet@yahoo.com
Date: 4 Apr 2007 09:25:59 -0700
Links: << >>  << T >>  << A >>
On 4 Apr., 17:35, Austin Lesea <aus...@xilinx.com> wrote:
> Ryan,
>
> Your metric is extremely simple.  Perhaps too simple?
Definitely too simple. But I need a first guess what might be
possible, not the final answer about the ideal FPGA. Therefore I don't
want to discuss all details, but only the multiplication rate which is
one of the limiting factors, which will boil down the choice to <10
chips. After this preselection I'll work out if additional logic, RAM
or IO will limit the performance.

> What is it that
> you wish to do?  1E12 multiplies per second is a bit too simplistic.
Yes? Then please tell me how to run 1E12 multiplies per second -
nothing else - for 100$, and we can continue to the next step.

> You need to consider the 'care and feeding' of this 'monster'.
>
> What is the resolution required? 18X18? or 9X9? Or really 25 X 18?
More like 36x36 which will increase the required number of FPGAs by a
factor of 4. I'd appreciate if you can suggest FPGAs with higher-
resolution multipliers that are more cost-efficient than those with
18x18 (combined to 36x36).

> Is it all multiplies, and no accumulates?
I do need accumulators.
> Hard to imagine a problem
> where no addition whatsoever is required.
I wasn't asking you to imagine the problem, but whether you know chips
that can do highspeed multiplication at low cost.

> Multipliers alone may not
> suffice.  What about accumulators?  What number of bits?  The DSP48
> blocks in the Xilinx architectures are intended for most common needs.
> The DSP48 in V5 also has the traditional 4 bit control (16 function) ALU
> as part of the DSP block.  Very wide AND, OR, XOR, etc. are all provided.
Yes, I guess the 640 DSP48-slices of the XC5VSX95T are the multipliers
that Sylvian mentioned. I don't mind if the FPGA is filled with
additional (then unused) logic unless it uses too much power. So
you're welcome to suggest xtreme DSP chips even if their multipliers
are used inside DSP slices.

> You should also consider how much SRAM is on chip.  If you have
> insufficient RAM, you can not "feed your monster."
With 1000 18x18 multipliers I won't need more than 8x1000x18=144kbit
RAM space.

>
> Similarly, IO is required to feed the RAM, and get the results.  You
> need to consider if the IO is a bottleneck (limits your performance).
It is not, because the computational intensive part is localized on
each chip.

Ryan


Article: 117590
Subject: Re: high number of multipliers / low cost
From: ryan_usenet@yahoo.com
Date: 4 Apr 2007 09:32:48 -0700
Links: << >>  << T >>  << A >>
> It would be interesting to know what you think "a multiplier" is - i.e. what
> word-length, and are you talking about fixed-point or floating-point
> operations?

Simulations show that 36bit fixed-point are sufficient. However for
later improvements we might change to floating-point calculation. Do
FPGAs with floating point multipliers/adders exist, or how can one
estimate the (emulated) floating-point performance given the fixed-
point performance?

Ryan


Article: 117591
Subject: Re: high number of multipliers / low cost
From: "Ben Jones" <ben.jones@xilinx.com>
Date: Wed, 4 Apr 2007 17:53:19 +0100
Links: << >>  << T >>  << A >>

<ryan_usenet@yahoo.com> wrote in message 
news:1175704368.383458.84460@l77g2000hsb.googlegroups.com...
>> It would be interesting to know what you think "a multiplier" is - i.e. 
>> what
>> word-length, and are you talking about fixed-point or floating-point
>> operations?

> Simulations show that 36bit fixed-point are sufficient. However for
> later improvements we might change to floating-point calculation. Do
> FPGAs with floating point multipliers/adders exist, or how can one
> estimate the (emulated) floating-point performance given the fixed-
> point performance?

Well, it's tricky and your mileage may vary a great deal, but you might want 
to take a look at the Xilinx Floating-point operator core datasheet. This 
will tell you how big and how fast the various FP operations will be 
depending on your desired wordlength.

Multiplication in floating-point is not really too much of an overhead 
relative to fixed-point, but addition certainly is much much bigger and 
slower.

Good luck,

    -Ben- 



Article: 117592
Subject: Interfacing the DAC0808 to FPGA
From: "Hrishi" <sankpalhrishi@gmail.com>
Date: 4 Apr 2007 10:13:19 -0700
Links: << >>  << T >>  << A >>
Hello,
        I m building a Function generator using an FPGA!! I m almost
done wid the Coding part in VHDL. I'd just like some help regarding
the interfacing of DAC0808 with the FPGA. Also  how th output
Amplitude variation can be done.!!!


Article: 117593
Subject: Re: TI Tap Controller std8980
From: "Amal" <akhailtash@gmail.com>
Date: 4 Apr 2007 10:15:29 -0700
Links: << >>  << T >>  << A >>
On Apr 4, 12:44 pm, "Amal" <akhailt...@gmail.com> wrote:
> Has anyone used std8980 model from FMF (http://www.freemodelfoundry.com/)? We are having some problems with the
> model and I was wondering if anyone has successfully used this model.
>
> -- Amal

Oh, one more thing, does anyone has a pointer to a good tap controller
model?

-- Amal


Article: 117594
Subject: Re: Does the XC3S250E-VQ100 exist?
From: Uwe Bonnes <bon@hertz.ikp.physik.tu-darmstadt.de>
Date: Wed, 4 Apr 2007 17:17:51 +0000 (UTC)
Links: << >>  << T >>  << A >>
radarman <jshamlet@gmail.com> wrote:
...
> but if I'm reading the datasheet right, it only needs two supply
> voltages - 3.3v and 1.2v. That will cut an extra switcher from the
> board, which somewhat makes up for the larger package.

If the 2.5 Volt is only needed for VCCAUX in the XC3S, there is no need
for a switcher. Quiecent current is well below 100 mA even for a XC3S1600E
and well suited for a low drop regulator from 2.5V
-- 
Uwe Bonnes                bon@elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------

Article: 117595
Subject: Re: Complex Baseband
From: "comp.arch.fpga" <ksulimma@googlemail.com>
Date: 4 Apr 2007 10:33:40 -0700
Links: << >>  << T >>  << A >>
On 3 Apr., 15:23, Ray Andraka <r...@andraka.com> wrote:
> You might consider one of the Matlab clones: Octave or I think the other
> is called Scilab.  I don't have experience with either, but from what I
> understand both will run matlab M files and have pretty good coverage of
> the matlab function set.

Scilab is similar to Matlab but not compatible, Octave is said to have
very good
compatibility to Matlab.
Scilab has a good Windows installer, Octave is better used under
Linux.

Kolja


Article: 117596
Subject: Re: Implement IIR Filter on FPGA
From: "Daniel S." <digitalmastrmind_no_spam@hotmail.com>
Date: Wed, 04 Apr 2007 14:16:52 -0400
Links: << >>  << T >>  << A >>
Gordon Freeman wrote:
>> Watch the values change in the accumulators as you add and subtract the
>> input values.
> 
> Hi everyone!
> Thank you for your reply!
> I used ModelSim to simulate. The result is the same when I canculate
> by calculator.
> But when I implement on FPGA, it don't work too.
> I design IIR filter with 10 orders. I use Matlab to generate
> coefficients for filter (b(k) and a(k)). For coefficient "b", I
> multiply with 2^14 and multiply with 2^5 for coefficent "a". After
> that I round them. These coefficients stored in LUT. I use SDA for
> filter. Because I think IIR filter include tow FIR filter. One filter
> with coefficient "b" and one with coefficient "a". Is it right?

Check your synthesis log to make sure your design did not get 'optimized' 
away. If you forgot some control signals somewhere, it is possible that 
synthesis deduced that some of your design had static elements, removed 
them to optimize, then deduced that everything else is now unconnected and 
removed that as well.

BTW, also make sure your VHDL agrees with your board's reset polarity.

Article: 117597
Subject: Re: high number of multipliers / low cost
From: Sylvain Munaut <tnt-at-246tNt-dot-com@youknowwhattodo.com>
Date: Wed, 04 Apr 2007 20:36:31 +0200
Links: << >>  << T >>  << A >>

>> What is the resolution required? 18X18? or 9X9? Or really 25 X 18?
> More like 36x36 which will increase the required number of FPGAs by a
> factor of 4.

Google for karatsuba, you can do it with just 3 ;)

Article: 117598
Subject: Re: high number of multipliers / low cost
From: "Daniel S." <digitalmastrmind_no_spam@hotmail.com>
Date: Wed, 04 Apr 2007 14:39:13 -0400
Links: << >>  << T >>  << A >>
ryan_usenet@yahoo.com wrote:
> On 4 Apr., 17:22, "Symon" <symon_bre...@hotmail.com> wrote:
> 
>> Hi Ryan,
>> Don't forget FPGAs have other resources apart from 'hard' multipliers.
> 
> If the sequential multiplier could be used in 'pipeline' operation
> (meaning the result is delayed by n clocks, but then a new result is
> produce in each cycle), this would be interesting, but I guess, it
> cannot?


If you want to infer pipelined multipliers with ISE, the basic coding 
template is simple and is the same for both hardware and fabric multipliers:

process(clk)
begin
   if(rising_edge(clk)) then
     multpipe0 <= inA * inB; -- pipe 0..2 are inA'WIDTH + inB'WIDTH wide
     multpipe1 <= multpipe0;
     multpipe2 <= multpipe1;
     multout <= multpipe2; -- You can truncate the result here if necessary
   end if;
end process;

This will yield one multiplier result each clock and have a latency of four 
cycles from input to output. Depending on what FPGA family you are using 
and your synthesis tools, you may need more or fewer pipeline registers - 
these will be either absorbed by the hardware multipliers (up to four for 
Spartan 2 and V2Pro, two for V4/V5) or distributed within fabric 
multipliers to improve timings.

AFAIK, there is no way to infer a sequential multiplier... all you can have 
is "large combinational blob" which is really slow and pipelined, both 
using roughly the same amount of FPGA slices when implemented in fabric. If 
you want sequential for whatever reason, you will have to do it yourself.

Article: 117599
Subject: Gray code in asynchronous FIFO design
From: "anand" <writeanand@gmail.com>
Date: 4 Apr 2007 11:57:19 -0700
Links: << >>  << T >>  << A >>
Why do we use Gray code in asynchronous FIFO? (I am aware that only
ONE bit changes in Gray code at a time, but what is the advantage of
that?)




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