[chbot] Simple robot programming

Hanno Sander hanno at mydancebot.com
Wed Jul 1 09:57:54 BST 2009


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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