Parallax Propeller
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From: Peter Jakacki on 18 Sep 2006 03:39 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 http://www.parallax.com/propeller/index.asp 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*
From: Jim Granville on 18 Sep 2006 07:19 Peter Jakacki wrote: > 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 http://www.parallax.com/propeller/index.asp > > 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? 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
From: David Ashley on 18 Sep 2006 12:56 Peter Jakacki wrote: > 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 http://www.parallax.com/propeller/index.asp > > The price has just been halved by Parallax to promote volume use. 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 -- David Ashley http://www.xdr.com/dash Embedded linux, device drivers, system architecture
From: Peter Jakacki on 18 Sep 2006 19:11 David Ashley wrote: > On the website it shows $25.00 for each chip, does that mean the price > is now $12.50? 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. > > 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... 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 http://www.xgamestation.com/ to see what is being done with the Propeller, WOW! > > 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. 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). > > 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. 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. > > I just can't see a killer APP for it at its current price. If the price > were $5 > possibilities could open up. 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. > > It sounds like a cool toy though. Alternative to the CEL architecture > and it's > available now. Programming both would be similiar I expect. 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*
From: Peter Jakacki on 18 Sep 2006 21:20
I have just uploaded some of my recent screen shots of the Propeller running VGA and TV displays. http://www.pbjtech.com/cpu/propeller/ *Peter* |