FPGA based processor vs. "hard" processor

I just finish reading the interesting thread of PIC vs AVR.  I am not
in the embedded area but have a related question.  In recent Xilinx
marketing stuff for Spartan-3 FPGA, it indicates that the 100K-gate
FPGA now reaches $2 a piece, and the costs of softcore 8-bit processor
(PicoBlaze) and 32-bit processor (MicroBlaze) are reduced to $0.10 and
$0.48.

Despite of the marketing hype, do you think that the FPGA-based
softcore processor can really compete with the "hard" processor
(such as PIC or AVR) in embedded application?

Thanks in advance. 

S.C.

The fpga cpu gets you just that: the CPU.
The $2 "CPU" parts will also have memory (Flash & RAM) & peripherals.
The memory can be made using FPGA resources, but it's inefficient.
Such peripherals as SPI, UART etc. can also be in FPGA. However, you 
won't get an ADC (which most MPU's now include).

fp wrote:
> I just finish reading the interesting thread of PIC vs AVR.  I am not
> in the embedded area but have a related question.  In recent Xilinx
> marketing stuff for Spartan-3 FPGA, it indicates that the 100K-gate
> FPGA now reaches $2 a piece, and the costs of softcore 8-bit processor
> (PicoBlaze) and 32-bit processor (MicroBlaze) are reduced to $0.10 and
> $0.48.
> 
> Despite of the marketing hype, do you think that the FPGA-based
> softcore processor can really compete with the "hard" processor
> (such as PIC or AVR) in embedded application?
> 
> Thanks in advance. 
> 
> S.C.
> 

fp wrote:

> I just finish reading the interesting thread of PIC vs AVR.  I am not
> in the embedded area but have a related question.  In recent Xilinx
> marketing stuff for Spartan-3 FPGA, it indicates that the 100K-gate
> FPGA now reaches $2 a piece, and the costs of softcore 8-bit processor
> (PicoBlaze) and 32-bit processor (MicroBlaze) are reduced to $0.10 and
> $0.48.

As always, watch for the spin.

a) FPGAs approach $2 only in 7 digit volumes, in 2007.
  Go via the Xilinx store, and you'll find $8.41/100 is a more
real-world price. The next largest one is $12.54

b) The core budgets are just that : core only, no CODE and no 
Peripherals. Usually they also ignore the Loader memory costs !!

So it is classic stone soup - if you took only the cores in
the PIC/AVR/80C51/RS08, they would also be in the 'some cents'

Also, if ADDING the FPGA processor bumps you up a FPGA size, then
the cost becomes a real +$4.13 in the above example, and that $4.13
can buy quite a lot of microcontroller-system these days (not just a core)!

  If you are lucky, and have enough fabric, and BRAM, spare, doing 
nothing, then a FPGA core can be almost free.

  So it depends on the design.

> Despite of the marketing hype, do you think that the FPGA-based
> softcore processor can really compete with the "hard" processor
> (such as PIC or AVR) in embedded application?

FPGA's will never touch the small microcontrollers.

Where a FPGA processor makes sense is when
a) You already have the FPGA doing other tasks, and have enough spare room
b) You need a Processor to assist
c) Good coupling between the Processor and FPGA is needed.
d) Multiple cores help the design

The weaknesses of FPGA are
* Code memory handling.
* A complete lack of Analog Peripherals
* High Icc costs
* Complex and narrow power supply ranges

  So, you should always 'reality check' your FPGA core, against 
something like a LPC2101, and make sure a smaller FPGA + Good uC is not 
a better solution.

  There are some interesting gaps :
  Most microcontrollers run direct from FLASH, and are tru single-chip 
solutions.
  However, FPGA cores keep edging up in speed, and are now over 200MHz, 
whilst microcontrollers are more flash-limited to 30-75MHz.
  That's the opposite of a few years ago, when the cores were slower, 
but more flexible.

Something has to happen to non-volatile storage speeds, or the FPGAs
will get something of a speed advantage.

-jg

fp wrote:
> I just finish reading the interesting thread of PIC vs AVR.  I am not
> in the embedded area but have a related question.  In recent Xilinx
> marketing stuff for Spartan-3 FPGA, it indicates that the 100K-gate
> FPGA now reaches $2 a piece, and the costs of softcore 8-bit processor
> (PicoBlaze) and 32-bit processor (MicroBlaze) are reduced to $0.10 and
> $0.48.
>
> Despite of the marketing hype, do you think that the FPGA-based
> softcore processor can really compete with the "hard" processor
> (such as PIC or AVR) in embedded application?
>
> Thanks in advance.
>
> S.C.

I think power consumption for an FPGA is not in the same league as the
AVR or MSP430's.

fp wrote:
> I just finish reading the interesting thread of PIC vs AVR.  I am not
> in the embedded area but have a related question.  In recent Xilinx
> marketing stuff for Spartan-3 FPGA, it indicates that the 100K-gate
> FPGA now reaches $2 a piece, and the costs of softcore 8-bit processor
> (PicoBlaze) and 32-bit processor (MicroBlaze) are reduced to $0.10 and
> $0.48.
> 
> Despite of the marketing hype, do you think that the FPGA-based
> softcore processor can really compete with the "hard" processor
> (such as PIC or AVR) in embedded application?
> 

As soon as you need a fourier transform co-processor...

Rene
-- 
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

steve wrote:
> fp wrote:
> > I just finish reading the interesting thread of PIC vs AVR.  I am not
> > in the embedded area but have a related question.  In recent Xilinx
> > marketing stuff for Spartan-3 FPGA, it indicates that the 100K-gate
> > FPGA now reaches $2 a piece, and the costs of softcore 8-bit processor
> > (PicoBlaze) and 32-bit processor (MicroBlaze) are reduced to $0.10 and
> > $0.48.
> >
> > Despite of the marketing hype, do you think that the FPGA-based
> > softcore processor can really compete with the "hard" processor
> > (such as PIC or AVR) in embedded application?
> >
> > Thanks in advance.
> >
> > S.C.
>


> I think power consumption for an FPGA is not in the same league as the
> AVR or MSP430's.

There's an understatement. Typical idle currents for AVR are in the
sub-milliamp range ( _well_ sub-milliamp), and (from the data sheet)
about 3.5mA active, 4MHz, Vcc = 3V

A small FPGA won't get below about 5mA idle (no internal clocks at
all). Run current is tougher becaue it depends on how many cells are
being toggled and I/O power, but a typical number to do the same as the
AVR is 10-15mA (using the SWAG technique).

The AVR in powerdown mode has a max Icc of 15 uA with the WDT and
external interrupts enabled, which suits me just fine.

There is a time and place for a soft processor, but even though I have
enough room left in a Spartan 3 in a new design, I still use an AVR for
system management (I power off the FPGA completely) and system startup
/ shutdown control simply because I can't afford the extra power
consumption.


Cheers

PeteS

"fp" <fpga002006@yahoo.com> schrieb im Newsbeitrag
news:1154742379.806952.19250@b28g2000cwb.googlegroups.com...
> I just finish reading the interesting thread of PIC vs AVR.  I am not
> in the embedded area but have a related question.  In recent Xilinx
> marketing stuff for Spartan-3 FPGA, it indicates that the 100K-gate
> FPGA now reaches $2 a piece, and the costs of softcore 8-bit processor
> (PicoBlaze) and 32-bit processor (MicroBlaze) are reduced to $0.10 and
> $0.48.
>
> Despite of the marketing hype, do you think that the FPGA-based
> softcore processor can really compete with the "hard" processor
> (such as PIC or AVR) in embedded application?
>
> Thanks in advance.
>
> S.C.
>

FPGA's are the right choice for high performance applications, like video
processing, specialized sd/ddr memory controllers, fast networking etc. etc.

It really doesn't make sense to use an 8bit soft ip for a battery operated
blood pressure tester or something similar.

However an fpga based lcd/tft controller with on screen user interface would
benefit from an 8bit ip.

In applications like networking, the choice of doing tasks in hardware or
software (on the same chip) leads to very high performance solutions at
minimum consumption of resources. You can implement a fairly complex network
controller @100MHz with a 16bit cpu in a small Spartan 3E chip for about 8$
in single quantities.
See:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=49926&Row=18546&Site=US


MIKE

-- 
www.oho-elektronik.de
OHO-Elektronik
Michael Randelzhofer
FPGA und CPLD Mini Module
Klein aber oho !

"fp" <fpga002006@yahoo.com> wrote in message
news:1154742379.806952.19250@b28g2000cwb.googlegroups.com...

> Despite of the marketing hype, do you think that the FPGA-based
> softcore processor can really compete with the "hard" processor
> (such as PIC or AVR) in embedded application?

Never - because by the time that the bleeding-edge silicon and the
buggy tools has yielded a working product, the available CPU's will
have better performance and lower price than the FPGA "solution"! It
is, I.M.O., not possible to beat the economics of the volume behind
the generic processors.

PS:

I have personnally watched a large telecom equipment provider do this
dance every 3 years or so when the pain from the last project
"leading-edge" blowout becomes forgotten. They just started again ;-).