Subject:
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Adapting the LMD18200
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Mon, 3 Jun 1996 20:38:01 GMT
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Original-From:
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Tom G. Brusehaver/Consultant Euler Solutions <tgb@bnu003.cncc.bnr*stopspammers*.com>
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Reply-To:
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tgb@bnrSTOPSPAM.com
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Viewed:
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1438 times
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Over the weekend I decided to use the LMD18200 H-Bridge devices for a
larger robot I am building.
What I did was simply remove the L293 chip and replace it with a 16pin
header and some rainbow ribbon cable.
Before you decide this is for you, here are the pros and cons (as they
came to me).
pro con
----- -----
Higher current motor control Minimum 12V to motors
Portability goes away
Probably need a heatsink Larger robot required
Expensive (~$18 ea).
The LM18200 is a really nice H-Bridge chip. Digi-Key lists them for
about $18, but they can be had cheaper. They seem quite robost, I
managed to short both digital inputs to a motor output (while the
motor was running) and nothing was damaged (handyboard, motor chip,
etc).
National has a datasheet in PDF format for this at:
http://199.2.26.194/pf/LM/LMD18200.html#datasheet
I looked at the schematic and found the L293's really only use 2 pins
for input. For motor 3, it is pins 1 and 2, and for motor 2 it is
pins 9 and 10.
------
/| |-----
/ | |---------- Motor
/ | LM |-----
/ |182 |-----
/ | 00 |--------GND (motor and signal)
| * | |--------motor power (12-55V)
\ | |--------hb pin 2
\ | |----- gnd (brake)
\ | |--------hb pin 1
\ | |---------- Motor
\|pin1|-----
------
Pins 2 and 10 connect directly to the motor. Pin 3 is pwm, which is
compatible with handy board pwm output. Pin 4 is a brake, and could
be connected to the handy board using one of the digital inputs, but
I decided to not use it. pin 5 is direction which is compatible with
the direction output on the handy board. Pin 6 is motor power, you
should make all your needs available here. Pin 7 is ground, signal
and motor power. Pin 8 is a current sense that might be useful into
an A/D port (properly scaled of course), and Pin 9 is a thermal flag
that could set off an interrupt or other digital input.
I have successfully got this working on a pair of motors, and the
different IC motor control values continue to work.
--
tgb@bnr.com
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