Parallax Propeller, why is it so overlooked?

The Propeller chip is unpopular for so may reasons: it is very limited compared with ARM Cortex and far from cheap.

The 8 processor model is difficult to design with and this puts people off but there are worse features to come - each processor has a very limited amount of memory (512 words is tiny) and access to a bigger common memory (still only a tiny 8k words) is time sliced and so very slow. The next big issue is that the chip has effectively no on-chip peripherals. A typical cheap ARM Cortex will have SPI, I2C, UARTS, timers, USB etc etc.

Several companies have attempted to dump peripherals and code them all in software - it's never popular because it's hard work and difficult to support in practice and always gives worse performance than dedicated peripheral functions. XMOS are currently plowing this furrow and have found a few niche applications but aren't breaking into the mainstream (they've inherited too much attitude from Inmos so I don't think they ever will make the big time.)

So while the Propeller is interesting, and can give good performance if you get a job that is a really good fit, it isn't  a patch on general purpose micros for general purpose jobs - and they make up most of the market. For niche stuff DSPs are much better at DSP, FPGAs are much better at massively // and can be clocked so much faster etc etc.

So right now I can buy an ARM Cortex with a 180MHz clock 1Mbyte Flash, >192kBytes RAM, on chip USB, Ethernet, Encryption/Decryption etc etc for about the same price - the Propeller just doesn't offer anything expect less stuff and more hassle.

MK

So right now I can buy an ARM Cortex with a 180MHz clock 1Mbyte Flash, >192kBytes RAM, on chip USB, Ethernet, Encryption/Decryption etc etc for about the same price - the Propeller just doesn't offer anything expect less stuff and more hassle.

.. and run a propeller emulation on it with 1:1 speed (probably - I am guessing here)

Several companies have attempted to dump peripherals and code them all in software - it's never popular because it's hard work and difficult to support in practice and always gives worse performance than dedicated peripheral functions.

Performance should not be an issue, at least not for statdard perpiphals (SPI, PWM, UART, I2C ...) those are all simple protocols. Indeed simple enough to implement them whith a few gates in hardware... that's how they were designed.

I'm not quite sure what you are getting at re. peripherals - are you saying that SPI, UART etc are better off in hardware or software ?

MK

Yep, that's what I meant when I said earlier that the XMOS has "special support logic" - it (and some other processors) are much better at bit banging than your normal micro.

Unfortunately the price that is paid for that (in the widest sense) has (so far) kept such processors out of the mainstream.

There's been a thread on E14 recently talking about the Snickerdoodle (I wish they had thought of  a less silly name) which is an even cheaper way of getting a Zynq (but no array processor).

MK

For my work stuff I use mainly ARM based micros with FPGAs for the hardware gymnastics (when required).

I rather like the idea of all the esoteric chips but they've never looked convincing enough to actually use (Propellor, Parelella, XMOS, GreenArrays GA144 etc)

re. Joey's comment on I2C - I do often bit bang I2C on micros because I've had so much trouble with the built in stuff in the past. But it does mean that the micro is busy all the time it's I2C-ing.

MK

No problem with fan boys 

I decided to go mainsteam (ARM) instead of niche (Xmos) despite I like the solutions in the niche products. PSoC and Xmos are very intresting (have dev boards lying aroud but no time to give them a closer look)

In the past I had an Inmos Transputer board which got me into programming but turned out to be not relevant on the market. Same with parallel programming, tile based rendering and many other technologies I had great hopes for. For hobby it is ok to look besides the mainstream, but if you have to make your living it's hard.

The propeller can bitbang spi @ 10mhz+ and the Uart is 2Mbaud... It doesn't have USB and a lot of other cool peripherals but theHALre coming in the prop 2. I personally think using a dedicated chip works just as well. I think ARM has taken off, it has the Arduino IDE on some chips and EMBed.. I think it would be more popular if the chips were easier across to port HAL layers across vendors and cortex 0/1/2/3/4 architectures. I have plenty of ARM boards which wont run Embed.

I guess I think of the propeller as having 8 little arduinos in one chip with internal lines to talk to each other. There is no need for interupts on the propeller architecture, but if you must have them they have been implemented in software. The propeller also has 16 hardware based counters which are fairly useful, Ive been reading a piece of software that uses 3 counters to receive RF and mix the IQ signals and output audio. This is all done with just an inductor antenna and a few other passives to make the props sigma delta A to D work. Which btw is very scale able up to 16 bits (most likely higher if proper care is taken during layout), its a resolution vs speed trade off.

The chip is very capable It is niche but it's niche works very well for hobby robotics and automation. Its also much easier to program without interrupts the deterministic nature is great... you can count on things getting done in a certain amount of time without interrupts disturbing them. Im not trying to sound like a fan boy, I guess the real reason I wonder why the arduino took off over the propeller is because Parallax already had the hobby market with the basic stamp, so why did hobbyist pick a 16mhz single core mcu over an 80mhz 8 core mcu? I personally think the PSOC chips are great and wish they actually had the arduino market they are easy to use and the digital fabric allows you to get your feet wet with an HDL when your ready, on top of being an ARM core.

The propeller can bitbang spi @ 10mhz+ and the Uart is 2Mbaud... It doesn't have USB and a lot of other cool peripherals but theHALre coming in the prop 2. I personally think using a dedicated chip works just as well. I think ARM has taken off, it has the Arduino IDE on some chips and EMBed.. I think it would be more popular if the chips were easier across to port HAL layers across vendors and cortex 0/1/2/3/4 architectures. I have plenty of ARM boards which wont run Embed.

I guess I think of the propeller as having 8 little arduinos in one chip with internal lines to talk to each other. There is no need for interupts on the propeller architecture, but if you must have them they have been implemented in software. The propeller also has 16 hardware based counters which are fairly useful, Ive been reading a piece of software that uses 3 counters to receive RF and mix the IQ signals and output audio. This is all done with just an inductor antenna and a few other passives to make the props sigma delta A to D work. Which btw is very scale able up to 16 bits (most likely higher if proper care is taken during layout), its a resolution vs speed trade off.

The chip is very capable It is niche but it's niche works very well for hobby robotics and automation. Its also much easier to program without interrupts the deterministic nature is great... you can count on things getting done in a certain amount of time without interrupts disturbing them. Im not trying to sound like a fan boy, I guess the real reason I wonder why the arduino took off over the propeller is because Parallax already had the hobby market with the basic stamp, so why did hobbyist pick a 16mhz single core mcu over an 80mhz 8 core mcu? I personally think the PSOC chips are great and wish they actually had the arduino market they are easy to use and the digital fabric allows you to get your feet wet with an HDL when your ready, on top of being an ARM core.

Yep, that's what I meant when I said earlier that the XMOS has "special support logic" - it (and some other processors) are much better at bit banging than your normal micro.

Unfortunately the price that is paid for that (in the widest sense) has (so far) kept such processors out of the mainstream.

There's been a thread on E14 recently talking about the Snickerdoodle (I wish they had thought of  a less silly name) which is an even cheaper way of getting a Zynq (but no array processor).

MK

For my work stuff I use mainly ARM based micros with FPGAs for the hardware gymnastics (when required).

I rather like the idea of all the esoteric chips but they've never looked convincing enough to actually use (Propellor, Parelella, XMOS, GreenArrays GA144 etc)

re. Joey's comment on I2C - I do often bit bang I2C on micros because I've had so much trouble with the built in stuff in the past. But it does mean that the micro is busy all the time it's I2C-ing.

MK

No problem with fan boys 

I decided to go mainsteam (ARM) instead of niche (Xmos) despite I like the solutions in the niche products. PSoC and Xmos are very intresting (have dev boards lying aroud but no time to give them a closer look)

In the past I had an Inmos Transputer board which got me into programming but turned out to be not relevant on the market. Same with parallel programming, tile based rendering and many other technologies I had great hopes for. For hobby it is ok to look besides the mainstream, but if you have to make your living it's hard.