Parallax Propeller

I haven't heard anyone talking about the Propeller since earlier in the year when it had just been released so I'd like to share my impression of it with anyone who is interested. BTW, I have been heavily into LPC21xx ARM chips the last year or so and this is something completely different.

I received a Parallax Propeller eval board last week and I have been hooked on it since. At the moment I have my board outputting 128 chars x

64 lines VGA text in color, outputting an independent TV text display in color, reading from an electret microphone directly (only Rs & Cs) and digitizing using internal sigma-delta into a buffer with delay and echo and spitting that out at the same time through another RC network straight into the monitors speakers. Meanwhile a PS/2 keyboard and a serial coms port as well as I2C is operating.

There are no glitches or hiccups, it just runs as smooth as, all this without external h/w support, I am impressed.

Sure, it doesn't have a 512K byte Flash, it loads it's software through the serial port or an external I2C EEPROM into it's 32K of main RAM which sounds a bit limited, but look what it can do with it! The Propeller is comprised of eight 32-bit processors each with it's own 2K byte RAM connected to a central hub with the 32K of main RAM and 32K ROM. You can find out more at

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The price has just been halved by Parallax to promote volume use.

Parallax have an active forum running but has anyone else had experience with this chip?

*Peter*
Reply to
Peter Jakacki
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Hi Peter, Yes, the device is something different. Nice to see something fresh, and I can see it would suit a class-room very well. (I also like the new Zilog ZNEO, as class-friendly, but it is not as radical as the nifty propellor)

-jg

Reply to
Jim Granville

On the website it shows $25.00 for each chip, does that mean the price is now $12.50?

I'm wondering what the target application would be for this. 32K isn't a lot to work with for software, you'd have to struggle to fit an mp3 player in that even if it's possible. mpeg-2 or -4 decoding...

I can see an approach where this device is a versatile helper processor for the main cpu, which would have much more memory. The parallax would be like handling the innermost loop in stuff. It would do its functions through bit banging in software say. DAC done with timer interrupt outputting samples at a steady rate. Video...I don't see how the chip could output a stable video signal fast enough without additional support circuitry. A low resolution 640x480 vga display requires a dot clock in the 25 mhz realm.

If you think of it as a low end programmable hardware type device then it sort of makes sense, your software turnaround times will be much faster than with FPGA development. Bandwidth in and out of the device will probably be a limiting factor. The 32K RAM size...that's too small for the cpu horsepower there is it seems to me.

I just can't see a killer APP for it at its current price. If the price were $5 possibilities could open up.

It sounds like a cool toy though. Alternative to the CEL architecture and it's available now. Programming both would be similiar I expect.

-Dave

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David Ashley                http://www.xdr.com/dash
Embedded linux, device drivers, system architecture
Reply to
David Ashley

When I purchased this last week the distributor charged me half price because he said that Parallax had just cut the price. Both Parallax's and his website still show the old price but I guess the website designer is a little slow.

Hey, I can't see how I would do MP3 with the current chip either, but then again take a look at the Hydra at

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to see what is being done with the Propeller, WOW!

Yes, I can see this processor will "sometimes" be better off as a slave processor, it could replace what would have required an FPGA. Part of the power of the Propeller lies in the 2 dedicated counters and video registers per cog. It is possible to synthesis frequencies up to 128MHz as each counter has it's own PLL. Some guy even stuck a bit of wire out of one of the ports as a Q&D 49MHz RF transmitter for a toy.

There are no interrupts because you can devote a whole processor to a function but the DAC function is implemented by using a counter (1 of

16) in delta modulation mode outputting at 40MHz so that only a simple RC filter is needed. The chip runs at 80MHz off a 5MHz crystal.

The same goes for ADC, although you could do sigma-delta with the cpu it is much easier to configure a counter for this.

The video registers can generate multiple 1024x768 VGA and/or TV video but it is up to a COG or two to process the frame data at this rate as there is very little RAM (at present).

The 32K does seem a little small when compared to the memory sizes of many 32-bit embedded micros now. However this sounds just like the PC programmer who looks at these whiz-bang 32-bit micros and who used to

100's of megabytes on the PC. You and I know you don't need that kind of memory but it sure is hard for the poor guy to get his head around it.

This chip is very new and I guess when they are selling volume they will be able to amortize their costs and also shift to a smaller process as their chips are 0.35um at present. Just think what it would mean if they shifted even to 0.18um.

Remember that this chip must be one of the very few that is even available in a 40-pin DIP pack which is what is required for those "great idea! let's try it out" moments. They also have QFP44 and QFN44 packs.

Don't expect to use C to program this chip but the Parallax have developed their own language called "Spin". You can program a cog in assembler or Spin, here is a sample of Spin.

_____________________ PUB Toggle(Pin, Delay, Count) {{Toggle Pin, Count times with Delay clock cycles in between.}}

dira[Pin]~~ 'Set I/O pin to output direction repeat Count !outa[Pin] ' Toggle I/O Pin waitcnt(Delay + cnt) ' Wait for Delay cycles _____________________

Using the supplied Propeller tool (IDE) for software development is extremely simple, there is practically no learning curve. A tap of the F10 will see your code compiled and downloaded into the chip within the blink of an eye, well that's certainly how I found it.

I can't wait for when they do come out with Propeller II but until then there are plenty of applications that I am planning with the current chip.

*Peter*
Reply to
Peter Jakacki

I have just uploaded some of my recent screen shots of the Propeller running VGA and TV displays.

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*Peter*
Reply to
Peter Jakacki

Pictures look interesting. The graphics consist of lines in some cases. Lines require memory. But this thing doesn't have enough memory for the display. So how are the lines displayed?

I can imagine a system where you just have a display list, say a list of lines to draw and a color for each. Then you have 2 small strip buffers, and you clip all the lines to one of the buffers and draw what would appear in that strip. Meanwhile you're displaying the other. What a headache.

Every step of the game you're going to be butting up against the hard 32K byte memory limit.

-Dave

--
David Ashley                http://www.xdr.com/dash
Embedded linux, device drivers, system architecture
Reply to
David Ashley

You have me intrigued. I have a project coming up that requires generating several HF signals count-locked to a 1kHz IRIG timing code, and this looks like a very interesting contender. Even if I decide to do it some other way, it's still a cute device. I shall read more. Thanks.

Steve

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Reply to
Steve at fivetrees

The chip looks nice to play with but @ $129 USD for a devkit it would put a hole in my wallet. That SPIN language looks cool too! I am just delving thru the datasheet to see how everything goes together.

-Isaac

Reply to
Isaac Bosompem

My local distributor has the DIP40 + EEPROM + CRYSTAL for $24.20AUD. If you look at the demo board schematics you will see that is all you need other than a 3.3V supply and a bit of board to mount it all on. Use two pencell batteries and skip the regulator if you like. There is nothing that the demo board has that you can't do yourself with bits from the junk-box. The serial port can be a simple 2 transistor affair.

In fact I think the absolute bare minimum would be just the chip and a

3V supply as you can boot this off the serial port and run it off it's internal oscillator. *Peter*
Reply to
Peter Jakacki

I've spoken with Intellasys recently and their architecture certainly looks to offer one hell of a lot of bang per buck. It's eccentric, it's *very* Chuck Moore, but if you've got an application that parallelises nicely and you aren't afraid of delving deep into FORTH it could well be just what you need. Their system looks like it'd be great fun to play with.

I've recently spoken with another fabless semi startup that's doing something similar, with an equally prominent name involved; it looks like the low-end micro is facing quite an assault from configurable parallel systems.

pete

--
pete@fenelon.com "he just stuck to buying beer and pointing at other stuff"
Reply to
Pete Fenelon

Being partial to forth as well, ill have to take a peek.

My only fear about these 'new' processors is picking one, getting heavy into it and having the company go poof..

At least with a 8051 or something you know it will still be supported even if one supplier dissapears.

Reply to
ziggy

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Reply to
Steve at fivetrees

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