Subject:
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Re: RCX Motor Controller
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 15 Jan 2003 14:57:45 GMT
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Viewed:
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895 times
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In lugnet.robotics, Carson Au writes:
>
> How does the RCX control the lego motor's? Using what?
>
> Some basic facts
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> forward - forward current
> backward - backward current
> Float - contacts opened
> Stop - contacts shorted
The RCX is equipped with MLX10402 H-bridge drivers (take a look at
www.melexis.com). These drivers have two inputs to control the H-bridge:
IN_1 IN_2
0 0 -> motor off
1 0 -> forward
0 1 -> backward
1 1 -> both motorpins switched to ground
The 1-1-combination usually has the same effect as motor off on normal motors.
This is why motor_x_dir(brake) does the same as motor_x_dir(off).
Inside the RCX, three MLX10402s are connected to a chip with eight D-Flipflops
(two of them are unused). So you only need to write one byte to access three
moto motors at once. BrickOS uses three 8-bit registers as PWM counters.
Take a close look at http://lepomux.org/brickos-patch/dmotor.c
I've put some additional comments on the motor bits into that file.
Gunther
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Message is in Reply To:
 | | RCX Motor Controller
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| Hi to all, How does the RCX control the lego motor's? Using what? Some basic facts forward - forward current backward - backward current Float - contacts opened Stop - contacts shorted carson (22 years ago, 13-Jan-03, to lugnet.robotics)
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