Subject:
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Re: interfacing PCs with LEGO?
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 24 Aug 2004 14:41:14 GMT
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Original-From:
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PeterBalch <PETERBALCH@COMPUSERVE.spamcakeCOM>
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Viewed:
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1019 times
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Hi Rob
> maybe you can help me out by recommending a good
> programmer and compiler for beginners.
Programmers are all much the same. Just get the cheapest you can find that
does the chips you want.
I have my own Basic compiler that I wrote before any others were available.
I still prefer it to the commercial ones I've tried - mostly because I'm
used to it and if I want a nifty new language feature I can just add it.
I'd be happy to supply it to anyone who wants it (for free). I just don't
want to spend hours a week on support.
> Even if you could recommend a book on
> PICs that would be helpful.
Sorry. When I learned, PICs were new and there were no books. (PICs also
had much fewer features and so were easier to learn!) If it were me, I'd
just borrow one from the local library. I've never been able to learn
programming by reading - only by doing.
The free application notes on the Microchip website are excellent. The
Microchip CD is free from Microchip and contains all the data sheets and
application notes.
> Do you have a website with some info on your projects?
http://ourworld.compuserve.com/homepages/PeterBalch
Most of my projects have been for commercial clients who want to talk to
extremely dull equipment like vending machines or traffic lights or
smartcards.
> Circuit diagrams?
For robots, I just look on the web and choose the circuit with the fewest
components. My only innovation is to replace the standard 6-transistor
H-bridge with a cheaper 4-transistor version. The transistors are used in
emmiter-follower mode instead of open-collector. The "left-hand" bases are
tied together and the "right-hand" bases are tied together and there are no
base-resistors. It takes up about half the board space and can't burn out
(as the 6-transistor version can). But it loses about 1.5V of drive voltage
compared to 0.8V for the standard 6-transistor version (but that's OK 'cos
I'm usually using cheap 3V-4.5V motors and a 6V battery).
If someone wanted to organise a circuit diagram library (as a companion to
this newsgroup; standard format, nicely indexed) then I'd contribute.
> Sample code for stuff like PID loops?
I've never done it with a PIC - only on a PC controlling an industrial
robot. For a PID loop, you need position feedback (which you usually don't
have with toy robots). And a PID is only really needed when the inertia and
momentum or the robot are significant and vary (e.g. cos the robot-arm is
holding something). For small robots, blindly ramping-up and ramping-down
the speed is good enough.
> Heck, I wish I could recruit you to do the electronics for my robots ;)
It's a deal. Once I've finished by two current robot projects and the other
dozen I'd like to do (and spent some time earning a living and a few
minutes a week on social life and family). It would be nice to think that
the two current projects will generate money but I doubt it. (The Picobotz
is finally meant to be in production after a mere 8 months delay and I'll
get the first pcbs for a four-legged-walker next week). I've not yet met
anyone who makes a profit designing or selling robots. I ask everyone who
claims to be in the business and all look a bit embarrassed and admit that,
actually, they're lucky to break even on the robots and make their real
living from something completely different.
All the best
Peter
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