propeller vs FPGA chips?

henry99

Are there any advantages/disadvantages of the propeller chip over a FPGA chip like the Xilinx?

Seems like the Propeller is actually an fpga wrapped up as 8 cogs. Please correct me if I'm wrong. Thanks!

rokicki

Yes. No. Done.

Very different solutions, very different problem spaces. Try writing a basic interpreter in Verilog/VHDL.
Now do the same thing in spin. Try making an LED blink in Verilog. Pay attention to the tool chain,
how long it takes to go from VHDL to blinking LED on the board. Same thing on the Prop.

Try to source 100 Props and the associated support circuitry; what's the unit price? Now do the same
thing for the FPGA you like. Now do the same thing for 10,000 units.

You could probably implement the Prop on an FPGA, but consider the effort required.

Leon

An FPGA was used during development of the Propeller, but it isn't actually implemented in one.

Leon

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Suzuki SV1000S motorcycle

henry99

I'm asking because I'm trying to figure out something to use for my next project. National instruments makes a Labview to VHDL converter that seems to make life pretty easy on an their FPGA but of course cost is way higher.

hippy

henry99 said...
Are there any advantages/disadvantages of the propeller chip over a FPGA chip like the Xilinx?

It really depends on what you are wanting to do.

The Propeller comes in a DIP package ( easy to use on breadboard and stripboard ) and comes as a cheap ready-to-use module by way of the ProtoBoard, programmed in a meaningful, easy to get to grips with language, with just a few seconds turn-round time for Rapid Application Development.

I've been able to achieve everything I want far simpler, easier and cheaper with the Propeller than with FPGA so for me the Propeller beats FPGA hands-down.

What's your criteria for best ?

Rayman

Another problem with FPGA is that it can take several minutes to compile and program... Compared to seconds with the Prop.

waltc

FPGA's do offer a lot of flexibility, want to roll your own processor that runs Java or Forth or even Pascal P-code natively? no problem on a Cyclone or Spartan. Chip and memory under $45.00(pcb not included).

Want your own unique 8 or 16 bit processor with built in VGA, etc. FPGA.

Want to roll your own retro or Amiga? FPGA is the way to go.

Check out Opencore for ideas of what can be done with them.
http://www.opencores.org

For a 16bit ForthCore check out Richard Haskell's paper at:
http://www.richardhaskell.com/files/ForthCoreMM.pdf

VHDL source can be found at his LearningByExample website.

FPGAs OTOH aren't friendly and require some serious upfront learning and planning if you go beyond just using them for glue logic or replacing some of the hard to find 74 series chips.

Still for the hobbyist who wants to roll his own CPU or build his own retro system, FPGA's are quite attractive(BTW thats my interest in them)

Price wise the entry point isn't bad. A $100 will get you a Xilinx Spartan dev board(Nexys2) and software.

Beau Schwabe

waltc,

As I understand it, certain key functions of the Propeller were tested using FPGA.· Running a complete Propeller FPGA equivalent would be cost prohibitive for a huge percent of our audience.


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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

nutson

My·favourite would be a board with an FPGA and a prop (and some memory) like this proposal·http://forums.parallax.com/showthread.php?p=755070·. Both have their weak and strong points; the prop is unbeatable for fast design and debug of·control programs,·and·an FPGA is very good·at·pin expansion and high speed data pre/post processing.·But you have to learn Verilog or VHDL to·program FPGA's.·····

Dennis Ferron

Thanks henry99 - I've been thinking the same thing, but as I'm familiar with how FPGA's work but have not actually USED an FPGA in a project, I was wondering if I'm the only one who noticed the similarity. I recently built a 6502 computer using a Propeller to implement the chipset for the computer, rather than using an FPGA. I was able to do not only "logicky" things like address decoding, but also things that are not so simple to express as logic, such as dynamically overclocking the 6502 during a special block transfer mode. During my block transfer mode, the 6502 executes NOPs while the address lines increment; I can clock the processor so fast during those times that it would cause corruptions in other instruction, but since nops are noncritical that's not a problem. Dynamically changing the clock rate with the Prop is just a matter of running different assembly subroutines with different instructions in their main loops; but that's not something that I can imagine would be easy to do with an FPGA. So it's an example where I think I was able to do something an FPGA could not easily do.

IMO, the #1 innovative thing about the Propeller is that it is a microcontroller that is powerful enough, and has the right architecture, that it can do some things that you used to need an FPGA for, and is (again IMO) the superior solution because it's easier to get started with, cheaper, and you can also program more complex things in it more easily as well, such as the Basic interpreter someone mentioned. That is, unless your application just requires such fast response or so many pins that an FPGA is required. In other words, I think it fills a mid-range gap where you need something more powerful than a PIC or SX, but where an FPGA is overkill.

Leon

Changing the clock rate dynamically isn't difficult with an FPGA. XMOS processors with their "software defined silicon" architecture have been designed specifically for replacing FPGAs in many applications, of course.

Leon

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Amateur radio callsign: G1HSM
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blittled

Dennis got me thinking about an idea I had to replace an ULA found in the ZX81 with a propeller. I was conerned with timing and thought a FPGA would do better but it may be possible since the propeller can run 20 times faster than the Z80

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What electronics need - MORE POWER!!!!!!!

dMajo

Beau Schwabe (Parallax) said...
waltc,

As I understand it, certain key functions of the Propeller were tested using FPGA.· Running a complete Propeller FPGA equivalent would be cost prohibitive for a huge percent of our audience.

And maybe also the PropII (http://picasaweb.google.com/jeffledger/UnofficialPropellerExpoNE2008#5238106968208036210).

Have you ever thought about releasing the Prop core as·IP ?!?

Dario