Subject:
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Re: mindstorms NXT
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Newsgroups:
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lugnet.robotics
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Date:
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Sun, 8 Jan 2006 19:36:06 GMT
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Viewed:
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7289 times
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In lugnet.robotics, dan miller <danbmil99@yahoo.com> wrote:
> If they're looking to the future, I would expect it to be a digital bus,
> much like something my robo-club has been thinking about. It could be I2C
> or CANN-based, or proprietary (unlikely). Six wires makes sense -- ground,
> bi-directional signal (2 wires; or maybe differential signal + shared bus),
> power for the controllers in the sensor/motors (5V regulated), power for
> analog parts (motors, LED's, sonar, 9V unregulated), and one for good luck
> (usually an extra ground for noise suppression).
>
> If so, then the encoders would be digital too, and you could imagine
> daisychaining (or star config with a muxer) multiple devices on a single
> port. It would just be a software matter to address them individually, and
> maybe some timing considerations.
>
> I really hope this is the case, but then again it may have been too
> expensive.
>
> When do we find out?
I just saw Lego's definiton of a servo motor. It resembles a industry servo, not
a hobby servo. In the hobby servo, the closed loop is done in the servo
electronics, but in the industry servo, the closed loop is done in the
controller. However, a digital bus would require that some "brain" to be
installed in the servos (like it is in the sensors). Also looking at the specs
for the NXT brick, one can see there are 2 controllers. A 32 bit ARM7 and a 8
bit controller. The latter one is probably the motor control unit. It's like
having 2 RCXs in one package: one takes care of the higher computations and the
other takes care of the motor control (one motor and one rotation sensor per
channel). This would reduce the price of the servos, by taking out the "brain"
from the servos and putting it in the NXT. But also this would make sharing one
port harder. Like I sayd in my previous post that Steve Hassenplug was so kind
to post it for me (thanks Steve!), 2 motors can share one port if only one
rotation sensor is in use. The power ussage of 2 motors running in parallel from
the same port would be similar to 2 motors running from the same port on an RCX,
which works fine. So it's all just making Y cables. But this works only in some
cases, not all. Oh well, we just have to wait and see...
Gabe
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Message has 1 Reply:
 | | Re: mindstorms NXT
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| (...) This all makes some sense, though it seems strange to put a digital board in the servos, but not do the control there. In any case, I think my first project will be to figure out how to use the USB port to connect the NXT to a more powerful (...) (18 years ago, 8-Jan-06, to lugnet.robotics)
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Message is in Reply To:
| | Re: mindstorms NXT
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| If they're looking to the future, I would expect it to be a digital bus, much like something my robo-club has been thinking about. It could be I2C or CANN-based, or proprietary (unlikely). Six wires makes sense -- ground, bi-directional signal (2 (...) (18 years ago, 8-Jan-06, to lugnet.robotics)
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