Subject:
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Re: moving in a straight line with two motors?
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 13 Nov 1998 20:00:08 GMT
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Original-From:
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Eric Brandwine <ericb@mitre.org^spamless^>
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Viewed:
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2511 times
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> > > > > "kp" == Kekoa Proudfoot <kekoa@Graphics.Stanford.EDU> writes:
> > I looked at kekoa's pictures of the disassembled RCX.... The motor
> > driver chips are ELEX 10402B / 9980A / 4597. About which I was able
> > to find absolutely nothing. Oh well.
kp> There needs to be a link to this somewhere:
kp> Peter Phillips pointed out a long while back (my messages from him are
kp> dated Sep 21) that the specs to the chip are here:
> > > Melexis AKA ELEX MLX10402 Motor driver IC in SOIC16 package
> > >
> > > http://www.melexis.com/site/10402/f_10402.htm
kp> If you look up the specs, you can find out for sure the rating on the
kp> drivers.
OK, 500mA per driver.
Which, if the rest of my handwaving was accurate, means that 2 motors
off 1 port will work.
The data sheet confirmed something else that I thought was happening...:
In1 In2
1 0 Forward turning
0 1 Backward turning in opposite direction
1 1 Brake motor is shorted
0 0 Off motor is disabled
Obviously 00 is the state of the RCX when it is off. When it is on,
the wheels are much harder to turn by hand. The RCX must default to
state 11 when idle. Not all motor drivers support this, but this one
does....
That means that there is no coast mode, the RCX starts
electromagnetically braking as soon as the motor is turned off. Also,
there is constant current leakage whenever there are motors attached.
Should be pretty low if the motor is not moving, but should climb a
LOT if the motor is driven by some mechanical force.
So, is there any way to disable a motor port in firmware, without
disconnecting the motor physically? Could be useful for long running
battery powered robots that do not need the motors moving all the
time.
ericb
--
Eric Brandwine, Systems Engineer | What is the definition of an engineer?
EricB@Mitre.org | Someone who solves a problem you
MITRE Corporation, McLean VA | didn't know you had in a way you
(703) 883-3319 F: (703) 883-1917 | don't understand.
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Message has 1 Reply:
 | | Re: moving in a straight line with two motors?
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| (...) This all depends. The table you gave (presumably from the date sheet), said: (...) Now, Lego uses Off to mean Brake and Float to Off ... (...) Well, you can set the motor to "float" and you do coast. (...) Please explain why there is (...) (26 years ago, 13-Nov-98, to lugnet.robotics)
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Message is in Reply To:
| | Re: moving in a straight line with two motors?
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| (...) There needs to be a link to this somewhere: Peter Phillips pointed out a long while back (my messages from him are dated Sep 21) that the specs to the chip are here: (...) drivers. I don't know if he told the rest of the list about this, if (...) (26 years ago, 13-Nov-98, to lugnet.robotics)
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