Subject:
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Re: Got my Handy, now what?
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Fri, 2 Jun 2000 03:29:11 GMT
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Reply-To:
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GLIVICK@PACBELLstopspam.NET
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Viewed:
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887 times
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Daniel Weatherford wrote:
> I ordered my Handy Board today, and am going to install it in
> an ice cream bucket named "BucketBot." (Better name? Please?)
> Well I know that I'll be hooking up my GP2D12 to it, and a sonar
> module (Polaroid 6500 hacked out of a Polaroid Sun 660 One
> Step), but I have a few questions:
>
> Does ANYONE know of a good way to make cheap encoders?
> I have wheels hooked onto servo motors with no electronics
> (Use a L293D) and need encoders. Should I use a Hall Effect
> sensor for this and a magnet or two per wheel, or an optical
> thingie, or what? I really need this sensor, and have NO clue
> whatsoever about how to implement it.
The The Handy Board Technical Reference has encoder information for
you. The ones I use are the QRB1114, and they are just two or three
dollars each. The Reference shows you how to wire them. See
http://lcs.www.media.mit.edu/groups/el/projects/handy-board/techdocs/index.html.
The encoders mentioned provide an analog signal. If you are handy with
electronics, you can digitize the signal with a Schmidt trigger. Here
is how the QRB1114 is wired digitally.
Diode is wired as normal. E (emitter) is wired to ground. 5V supply
hooked to 47kb resistor which
is hooked to C (collector). C is the hooked into the input of a hex
Schmidt trigger (74HCT14) output
of Schmidt trigger goes into MCU port. It is suggested that a .01 to .1
capacitor be put from
Schmidt trigger input to ground to eliminate spikes from triggering
Schmidt trigger. (This information came to me via Doug Leppard. I've
done it and it works, but it isn't necessary.)
The software to use these encoders already exists as well. See the
"shaft encoder" link at
http://lcs.www.media.mit.edu/groups/el/projects/handy-board/software/libs.html.
You can use the slow ones and probably have no problem. I you want to
speed things up, since the encoder runs in the system interrupt, you can
rewrite the .asm file to collect all the encoder data at one time with
one read, and leave off the velocity part to decrease the time used in
the system interrupt. While you are about it, you can add a way to shut
off the encoder data gathering all together while the wheels are not
turning, and that makes things much faster. If you need a hint how to
do this, email me privately and I'll send along my code that runs four
sensors.
Keep in mind that when you make encoder targets, the black stripes need
to be .10 wide, while the white ones can be much narrower. My white
ones are .04 wide, and everything looks fine on an oscilloscope.
>
> Is there anyway to modify the Handy to take a pre-regulated
> +5v supply? I have a couple LM2596T-5.0 5Volt 3A Simple
> Switcher regulators (Order today! They're great! Get samples
> at www.national.com and a 100uf cap and a 66uh - 100uh
> inductor, and you're ready to go!) and have had bad luck with
> the 7805 regulators (which happens to be on the handy...).
> I MELTED a 7805 once, it got SOFT to the prodding sharp
> object and ceased to provide 5 volts. And I was running only
> a HC11, L293D (Logic only, not motor power), Max232, and
> a HS300 servo.
I have used a whole bunch of different boards, including two Handy
Boards, and I've never heard of anyone burning one of these things up.
I broke one once by dropping something on it, but that doesn't count.
If you are worried about overloading yours, either heat sink the thing
or provide a separate regulator board for your high current devices.
Just keep the grounds hooked together and you should be fine (you know
about Vrl and Vrh, so you won't have a problem dealing with that).
Other than that, since it isn't broke, don't fix it.
> Thanks to that, I tried hooking up my servo
> to the +12v rail, and poof... no more servo, even screwed up
> the motor (doesn't turn with any voltage now - didnt think
> that possible). Well, enough rambling, is it possible?
Nope. Impossible :-).
> I don't
> really want to cut traces or anything (besides the pullups on
> the analog input, and I will probably end up desoldering that
> whole resistor network).
You can just cut a trace for the GP2D12. The pullups don't hurt
anything else that I know of. Here is one site that talks about that
(off the Handy Board site):
http://condor.informatik.uni-oldenburg.de/stueker/GP2D12/ and here is
another:
http://www.acroname.com/robotics/info/examples/GP2D12-1/GP2D12-1.html.
>
>
> What pyro sensor would you recommend for a fire-fighting bot?
Don't know for sure how it would work on finding candle flames, but the
Eltec sensor on this page comes in a kit that includes a fresnel lens.
http://www.acroname.com/robotics/parts/R3-PYRO1.html Here is the page
on the same site that shows how to hook it up:
tp://www.acroname.com/robotics/info/examples/eltec-1/eltec-1.html.
Beware however of the sample code. Steve (owner of Acroname) writes in
C, not IC, so he doesn't know that C++ comments are not recognized by
IC. Use /* instead of //. and close with */.
>
> I want to cruise by a room, point the sensor at it, and see whether
> or not the candle's in there. One sensor pack on Acroname said
> that it could do that, but I can't remember what it's called, and
> was wondering if there were any suggestions. I am NOT going
> with the Eltec, it just won't work for me.
Oops. Well, maybe others have an idea how the Eltec works, or know of
other sensors.
Gary Livick
Tiny HC11 products for your robot
http://www.teleport.com/~raybutts/
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Message is in Reply To:
 | | Got my Handy, now what?
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| I ordered my Handy Board today, and am going to install it in an ice cream bucket named "BucketBot." (Better name? Please?) Well I know that I'll be hooking up my GP2D12 to it, and a sonar module (Polaroid 6500 hacked out of a Polaroid Sun 660 One (...) (24 years ago, 2-Jun-00, to lugnet.robotics.handyboard)
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