[chbot] Simple robot programming

Thu Jul 2 03:17:37 BST 2009

Hanno

The propeller looks great, and is a fantastic choice for many projects.
I would certainly consider it for a variety of things!

However, ATMEGA wins for me on the following:
* Community: I hear about Arduino projects on the web sites I frequent.
I have friends using Arduinos that I can refer to. The trend is
interesting: http://www.google.com/trends?q=parallax%2C+arduino
* Price: Pre-built boards are about the same, but price for ATMEGA chips
can be a lot less (more range).
* Openness: Available from multiple vendors. Code written to run on a
ATMEGA can be ported to other processors.
* I like Italy :) - except for the scooters at night!

The propeller is more flexible and is faster, but  I am not looking for
a powerful micro-controller because the main processing is to be done in
Linux on a router, or on a Windows laptop (via the wifi connection).

BTW: I got the robot working last night (just)! Batteries were not
right, and motors had no gearing, so I need to work on that but
proof-of-concept is going very well :)

Cheers

Morris

On Wed, 2009-07-01 at 20:57 +1200, Hanno Sander wrote:

> I recently started a thread on the Parallax forums trying to see how
> to make the Propeller even easier to use.  It's a very capable chip
> (for proof see all the things I've done with it) but many consider it
> the easiest to use chip available today.
> 
> Pros:
> - Simple language
> - Simple toolchain- It takes less than a minute to get started
> (download the tool, type your first program to blink led's, compile to
> memory).  A typical compile/upload takes around 2 seconds
> - 32 general purpose IO pins that you can use however you want
> - Big community (>100,000 forum posts, prebuilt objects to do pretty
> much anything)
> - Available in DIP package or all sorts of pcb's
> - No interrupts, completely deterministic, comes with 8 processors
> - 32bits, so you don't have to worry about large numbers
> - 32kb memory on board, with easy expansion to gb's via sdcard
> - fast (160mips), low power 60mA at 3V
> 
> If you're committed to using many thousands of controllers I
> understand the desire to save a dollar or 2 to go with a less capable
> processor.  Otherwise, I highly recommend the Propeller- easy to get
> started and capable enough to do pretty much anything.
> 
> Hanno
> 
> 
> 
> On Wed, Jul 1, 2009 at 8:01 PM, Richard Jones<rjtp at ihug.co.nz> wrote:
> > A couple of other perspectives on lowering the bar of entry to robotics:
> >
> > 1. Simple howto's such as this one on AVR:
> > http://www.tuxgraphics.org/electronics/200411/article352.shtml
> > There's no rocket science in there, but everything is gathered in one place
> > with a nice progression to a low cost open ended platform that does not
> > have the limitations of simplified approaches.
> >
> > 2. I have a sneaky feeling that if you could join scratch to a robot you
> > could get 6 year olds moving robots around in no time:
> > http://scratch.mit.edu/
> >
> > Richard
> >
> > On Wed, 1 Jul 2009 18:39:33 +1200, jimmy allen <jimmy1248 at gmail.com> wrote:
> >> you could use flow charting or structure diagraming
> >> this is how my programaming teacher gets us to plan our code and it
> >> gives a visual feel for how a program is going to work
> >>
> >> On 7/1/09, Morris <skibear at gmail.com> wrote:
> >>> Thanks for the summary and links!
> >>>
> >>> classicladder is interesting! Looks to be active and a lot more than a
> >>> simple ladder logic editor/executor.
> >>>
> >>>
> >>>> I don't know whether the execution engine is separated from the drawing
> >>>> tool. The web-page was last updated in 2009, so it might still be
> >>>> maintained.
> >>>
> >>>
> >>> "It can run on little embedded platforms (no GTK interface dependance,
> >>> and number objects to allocate for less memory usage)." strongly implies
> >>> that the execution engine can be used stand-alone. However I suspect it
> >>> would not be a trivial amount of work to get it to the point I could use
> >>> it for my own uses!
> >>>
> >>> Cheers
> >>>
> >>> On Wed, 2009-07-01 at 17:18 +1200, Stephen Irons wrote:
> >>>
> >>>> A PLC is just a robot used to control industrial machinery, and PLCs
> > can
> >>>> do a wide variety of tasks. IEC 61131-3 specifies five languages for
> >>>> programming PLCs: Ladder Diagram (LD), Instruction List (IL),
> > Structured
> >>>> Text (ST), Function Block Diagram (FB) and Sequential Function Chart
> >>>> (SFC). IL is exactly the same as LD, except using text notation rather
> >>>> than diagrams. ST is a Pascal-like programming language and adds
> > nothing
> >>>> that any other imperative language can provide, and is probably not as
> >>>> well-defined as modern languages.. FB adds the ability to incorporates
> >>>> nested blocks of the other languages, and is very useful. SFC adds
> >>>> state-machine like behaviour.
> >>>>
> >>>> The combination of LD, FB and SFC is very powerful.
> >>>>
> >>>> As Charles mentioned, there are at least three parts to the system: the
> >>>> drawing tool, the compiler and the execution engine. An
> > almost-essential
> >>>> additional part is a debugger.
> >>>>
> >>>> In a previous job, I ported a (commercial) PLC execution engine to run
> >>>> on a 2 MHz 68HC11, so a WRT-style router will certainly have the oomph
> >>>> to do it.
> >>>>
> >>>> The drawing tool, compiler and debugger were Windows-hosted.
> >>>>
> >>>> The drawing tool included support for all five IEC 61131-3 languages.
> >>>> The drawing tool also included software-engineering utilities such as
> >>>> version control, documentation generation, etc.
> >>>>
> >>>> The compiler generated byte-codes that were loaded into the target and
> >>>> run.
> >>>>
> >>>> The debugger connected via any available channel (of course, you had to
> >>>> port the communication code), and you monitor the states of inputs,
> >>>> outputs and variables, could set breakpoints and watchpoints in all
> >>>> sorts of ways.
> >>>>
> >>>> The execution engine was very standard ANSI C, so could be ported to
> >>>> just about anything.
> >>>>
> >>>> The name of the system was IsaGraf, and they are still around. The
> > whole
> >>>> system cost a lot, but was far cheaper to buy than to develop
> > ourselves.
> >>>>
> >>>> As far as I know, there are no Linux-hosted tools that do all of this.
> >>>> However, there are a number of places to look:
> >>>>
> >>>> http://membres.lycos.fr/mavati/classicladder/ includes LD and SFC. I
> >>>> don't know whether the execution engine is separated from the drawing
> >>>> tool. The web-page was last updated in 2009, so it might still be
> >>>> maintained.
> >>>>
> >>>> http://mat.sourceforge.net/ looks interesting, but they don't seem to
> > be
> >>>> very active: last updated 2006.
> >>>>
> >>>> Stephen Irons
> >>>>
> >>>>
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