BS2 v Propeller

AIman

I started a discussion in the robotics forum under Finite State Machines and·am· now looking at using a propeller chip instead of a BS2.

If there is any feed back on the pluses or minuses of the BS2 v the Propeller I am all ears. At this point I can go either way.

Mike Green

The Propeller is much more sophisticated than the Stamp, much higher performance, and much more powerful. The interpretive language (SPIN) is pretty easy to use and very powerful in its own right. The amount of memory is greater than what most of the Stamps have (32K) and it's monolithic (no slots). There's no strict limitations on numbers and sizes of variables (limited only by total available memory). There's floating point capability and it's fast. The Propeller can do a lot of I/O by itself (with a few passive components) including video (TV and VGA), easy D/A and A/D capability, PS/2 keyboard and mouse. Complicating this: It's not a hybrid circuit with a built-in voltage regulator. The chip works at 3.3V and requires some precautions and external components (usually just resistors) to be happy talking to 5V devices. Some of the newer commands (LCD,I2C,1-Wire) are just now being implemented for the Propeller and using them is not as simple as it is with the Stamps, although it's not hard. Mostly, it's word-ier. You have to write more since they're procedure/function calls rather than built-in statements.

I'm biased towards the Propeller. Most new ICs now are 3.3V or can work with 3.3V signals. The serial input/output is fully buffered and full duplex so you won't miss a character if your program is busy doing something else. The same thing's true of
most other I/O in that they're handled independently (by other COGs on the chip). You can write your own multiprocessing routines in SPIN and you can mix SPIN and assembly (with some restrictions due to the way the chip works).

RinksCustoms

BS2, no , wait, ... BS2px specs(THE fastest Stamp available!) vs Propeller specs, DING!, DING!
Program memory: BS2px - 8x2KBytes . . . . | Prop - 32KBytes
MPU Cores. . . . . : BS2px - 1 . . . . . . . . . . .| Prop - 8 syncronizable COG's / shared rescources
MPU speed . . . . .: BS2px - 32MHz Turbo . . .| Prop - Internal RC/External crystal/freq-in DC to 80MHz compile/runtime config
Instructions/sec . : BS2px - ~19,000 . . . . . .| Prop - ~ 20,000,000 (or so i've read in other threads, i think this is a calculated #)
Proccessing . . . . : BS2px - serial . . . . . . . . | Prop - parallel
I/O lines . . . . : BS2px - 16 + 2 dedicated . . | Prop - 32 (after final program first loaded to EEPROM, 2 I/O's for I2C EEPROM - recomened)

Features - BS2px : Not very familiar with this version, i believe it has a 128 byte "scratch pad ram" and I2C innstructions built in

Features - Propeller : Global 32KB ram, per COG or internal proccessor (8) (included video generator, 2 specialized I/O assistants for freq synth ADC opp PWM & more!, 2KB local ram, I/O register, I/O direction register, separate PLLnX tap capability), true 32bit parallel proccessing @ up to 80MHz, a 100% parallax product!, and more i'm sure i forgot.

Despite that it's a 3.3V device this is about it's only shortcomming that i can think of vs ANY Basic Stamp! Spin, as i'm finding out, requires an open mind for a fresh concept of programming. The concept, comming from a stamp P.O.V., is more diffucult than the language.
I've come across rumors that the prop was overclocked to crazy speeds stable @ up to 100MHz & barely stable around 160+MHz region, lol talk about critical mass!

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Definetly a E³ (Electronics Engineer Extrodinare!)
"I laugh in the face of imposible,... not because i know it all, ... but because I don't know well enough!"

Post Edited (RinksCustoms) : 8/13/2006 5:13:42 AM GMT

Tracy Allen

It's like comparing an apple to an orange tree.

The Stamp is way simpler and easier for a beginner, but with experience and with help from a few external circuits and a penchant for minimalist thinking you can take it far.

The Prop can run circles around the Stamp, as seen in the spec sheet advantage,but it also has power enough to daunt the beginner or anyone on the first rungs of the its particular learning curve .

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Tracy Allen
www.emesystems.com

El Paisa

RinksCustoms said:

Despite that it's a 3.3V device this is about it's only shortcomming

I would not call this a shortcoming.

It is reality,·todays electronics needs to run faster and consume less power.

If anything, I will say the 5v devices·are old relics of the past.·

AIman

So does the propeller chip come with a manual or instruction book on the language or is there a down load? I didn't see anything on the Parallax website that was downloadable.

Are there projects and/or books·to help the learning curve or is it assumed that a certain level of knowledge exists?

Larry

there is a manual for sale on the website www.parallax.com

or a download of the same at www.parallax.com/dl/docs/prod/prop/WebPM-v1.01.pdf

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Mike Green

There are examples, hints, and some documents on this forum. They haven't been assembled into a formal book, but there's no shortage of information.

AIman

I tried the download and my computer couldn't pull it. So, lets look at this another way.

What would I need to get started with a Prop?

Does Parallax have a kit that contains the chip, board·and a book? I didn't see any when I checked but could have been in the wrong place.

AIman

I just saw that Parallax is coming out with a starter kit August 31.

Mike Green

The Propeller Starter Kit is not out yet, but it's just the Propeller Demo Board Kit and the Manual packaged together. You can order just the manual if you want. Propeller also sells the PropStick which is a Propeller chip mounted on an assembly with the crystal, boot EEPROM and a serial adapter for downloading from a PC. The whole thing is designed to plug into a generic breadboard. There are some other parties that sell Propeller boards like <http://www.wulfden.org/PRC/&gt; which is configured for plugging in lots of servos for robotics work, but is really more flexible than that. The Hydra is due out soon from Parallax and is a board (and manual) intended for advanced video graphics for gaming.

The choice you make depends partly on what you want to do with it. If you mostly want to experiment with the Propeller and see what it can do, you might get the Demo Board and Manual. The Demo Board has Video and VGA outputs and PS/2 keyboard and mouse inputs. It also has a microphone and a stereo headphone output. There's a small breadboard with 8 Propeller I/O pins accessable nearby. If you want to develop an application with the Propeller, I'd suggest the Wulfden board since it doesn't commit any of the I/O pins, yet you can easily add the parts for a PS/2 keyboard and video output. The parts are just the connectors and a few resistors, nothing fancy.

Post Edited (Mike Green) : 8/14/2006 3:36:03 AM GMT

AIman

What I want to do is build a robot to help my wife with some simple chores around the house (like sweep). It is designed with 6 legs and·two grippers. The legs for going up the step into the living room and the grippers to hold the broom. It calls for·running 7 sonar around the body and 4 IR; 2·in front and 2·in·back for edge detection and clearance sensing.

Given that each leg will need 3 servos (1 for each joint and one for travel) and each gripper will need 5 servos (1 for the elbow, one for the base, one for the wrist, one to turn the wrist and one to grip) this gives an immediate need of·28 useable items not including moving the broom.

I could go with a simple wheeled robot and reduce things down significantly, but then run into problems like going up and down the step for the living room.


Post Edited (AIman) : 8/14/2006 7:53:28 PM GMT

Mike Green

You have a couple of choices. For the computational demands, you're going to want a Propeller. It's got the memory and the speed. You've already run out of I/O pins though. You need 28 for the servos, 7 for the sonar, and 2x4 for the IR for a total of 43. I suspect that once Phil has his B&W camera done, you're going to need one of those and maybe a tilt/pan head for it with 2 more servos. How about planning now for using 2 Propellers? I would substitute a 24LC1024 EEPROM for the standard 24LC256 boot EEPROM. That way you can have additional storage for room maps, action lists, etc. You'd have some extra pins left over that you can use for a PS/2 keyboard and video out to make it easier to test and configure the robot.

If you don't want to use a second Propeller, consider a pair of Parallax Serial Servo Controllers at $39 each. They can handle up to 32 servos total (16 each).

Considering what you're going to spend on all that hardware, you might as well get 2 Propellers.

Post Edited (Mike Green) : 8/14/2006 9:27:46 PM GMT

AIman

Thanks for the input.

AIman

FYI - I downloaded the SDK studio and it looks to be pretty good so far.