A few specific questions about the propeller

danielt

Hello,

I am thinking about purchasing the propeller Education Kit (Prop stick USB) and committing to this platform for some time. But before I do, I have a few specific questions.

I have been using the Arduino for various stepper and servo experiments for the last year or so. I feel I know the basics. But I have hit the point in my projects where I feel I need to know more low level stuff about micro controllers. I am wanting to run six stepper motors simultaneously. Their position will be controlled in real time via a 3D animation program called Maya. I'm told I need to look into interrupts on the Arduino to get this to work the way I would like. But I feel that I will be hitting the hardware limits of the Arduino if I am going to be using six or more steppers each using interrupt routines.

I watched a few of the propeller webinars and it looks like it will fit the bill nicely without me even having to understand interrupts. Basically I have two main micro controller requirements for my project:
1. The Ability to run a loop for each stepper motor as parallel processes. Any one of these loops will need to be able to stop or change direction at any time without effecting the other loops. While each loop is running it's needs to somehow continuously check serial for new motor position input.
2. The ability to also read incoming data the same as above, but this time off of an SD card. I would like to be able to read in some position data to ram, start the motors running, then, as the data is read off the ram, prepare for the next few lines of data to read in from the same file on the sd card. I am wanting to be able to make this happen in the background without the motors skipping a beat.

Just wandering/hoping if the propeller is capable of doing the things I mention in the two points above?

Also, should I be looking at a basic stamp kit first (to lean how a micro controller works), or do you think I can manage the above without too much trouble with my Arduino experience?

Sorry for such a long post right off the bat. If you are interested in the project I am working on you can check it out here:
danthompsonsblog.blogspot.com/2009/04/diy-motion-control-rig.html
danthompsonsblog.blogspot.com/search/label/Motion%20Control

Leon

There won't be a problem with six steppers and an SD card; you could devote one cog to each motor and another to the SD Card, with another connected to the PC for debugging. If you have used an Arduino you shouldn't have too many problems using the Propeller, although you might need to get into some assembly language programming. You should be able to find ready-made functions to do most of the work, but they might need some modifying.

Leon

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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

danielt

Fantastic! Thanks for the reply. The only other thing I might want to do further down the track is link to another propeller chip to drive more than six motors. Is it possible to link them together in this fashion?

Leon

Several people are using two propellers together like that. I thought of running two steppers off one cog, but you'll run out of pins. There are other solutions, of course.

Leon

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

Post Edited (Leon) : 6/1/2009 10:16:05 AM GMT

danielt

Hmm, maybe I will wait to ask about those other solutions when I arrive at that point. But that's good to know. Thanks.