Alt-BEAM Archive
Message #00722
To: beam@corp.sgi.com
From: Justin jaf60@student.canterbury.ac.nz
Date: Sun, 21 Feb 1999 20:05:22 +1300
Subject: [alt-beam] It works, but I don't know how... explanations welcome :-)
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I was attempting to set up motor drivers such that while there is a
constant input into the inputs, the solar engine triggers the activation
of the motor drivers (either by enabling them, or by powering them). The
only ones I have on hand are 74HC245's nicked from a microcore (It's
Sunday evening - the electronics shops are closed), which don't seem
very well suited to the task at hand.
Anyway, I was using an LED to indicate when the solar engine was firing,
and during one of my rewirings, the LED ended up between the se output
and the driver enable I was playing with.
And everything sprang to life.
I don't quite understand why the LED made all the difference (this is a
case of orang-utan electonics :-), and am interested to find out, as the
circuit is now _technically_ doing what I wanted it to do, but seems to
be losing a fair bit of power to the drivers while not engaged, among
other things (my assumption is still that I'm going about this in very
much the wrong way).
The circuit is attached. It's a bit rough and quite inconsistant (rush
job) and doesn't detail the sensor-control circuit (I assumed this
irrelevant at the time, however I just remembered stuff that might
indicate otherwise. Ah well.) Hopefully it'll explain what I've done
though.
If I replace the LED with anything else (diode, photodiode, short,
resistor, etc) it won't work. The amount of light falling on the LED
affects things however (seems to change duration or cutoff of drive),
which might turn out to be useful, but at the moment is not.
This stuff is experimentation for a photovore BTW. Those eagle eyed list
readers will notice that recently I've been bugging you with several
other weird questions or problems; my electronics theory is not yet
advanced enough for me to avoid the stupid or innefficient solutions
when faced with a problem (But I am learning :)
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723 Sun, 21 Feb 1999 08:16:53 +0100 (CET) [alt-beam] Re: hmmm...i wonder which subject beam@corp.sgi.com Steven Bolt On Sat, 20 Feb 1999, Terry Newton wrote:
[ uP walker with emulated Nervous Net ]
> I want to try coupled bicores and the Stills/Tilden arrangement
> where the microcore is saturated. to try, not to be cool, not to
> make it smart...
> >Will that be a 5-motor walker?
> I'd love to create with 5 but I'll probably stick with 2, the chaos
> of that setup facinates me (and cheaper). I want to try the setup
> where one motor is horizontal and the other vertical. I also want
> to do more study on simple learning systems that can handle soupy
> bodies without mental failure. Face that problem head on!
Courageous, is the word that comes to mind :)
I look forward to reading your excellent documentation.
And I wonder if this would not be an application for one of the
ATmega's. The smallest (603, I think) gives you 64K of flash, 4K
sram, 2K eeprom, assorted other goodies like a 10-bit ADC,
analog comparator and watchdog, and up to 6 MIPS. All in a handy
1mm thin quad flat package of about 15mm x 15mm. Runs at 3V, 3mA
(4MHz). Down to a few uA when asleep. A fair amount of room for a
not too complicated learning system, and you could write it in C
(free compilers are appearing).
Success!
Steve
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# sbolt@xs4all.nl # Steven Bolt # popular science monthly KIJK #
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