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Subject: 
Re: mindstorms NXT
Newsgroups: 
lugnet.robotics
Date: 
Thu, 5 Jan 2006 22:49:35 GMT
Viewed: 
7807 times
  
In lugnet.robotics, Ross Crawford wrote:

Well, I hope they are also planning a smaller motor, without RPM sensor. I'm
sure there will be many situations when I'm happy to sacrifice accuracy for
size.

ROSCO

Actually, the RCX outputs 0's and 1's to power the motors as it is right now.
It uses Pulse Width Modulation (PWM).  Basically for 1/3 power 1/3 of the pulse
is 1 and the other 2/3 is 0.  For full power, the signal is all 1.  This creates
a non-linear input/output curve, but works.

http://www.restena.lu/convict/Jeunes/ultimate_stuff/speed.htm

So all all you have to do is crimp your lego wires into a RJ11 and connect it to
the NXT and send it a digital PWM signal.  Voila!  Your old motor works again.

Of course, someone will have to build a block in "LabVIEW" to send the PWM
signal to the motor.  Easy as pie if the software allows this.

Matthew C. Ruschmann
http://superpositioned.com



Message has 2 Replies:
  Re: mindstorms NXT
 
(...) I doubt that will do what you want. The RCX motor ports are equipped with motor drivers - ICs that can provide rather a lot of current, switch direction, and even short circuit the port. The digital wires would be I/O, not meant for noticeable (...) (19 years ago, 6-Jan-06, to lugnet.robotics)
  Re: mindstorms NXT
 
(...) I think that saying the RCX outputs 0's and 1's to the motor may be a bit misleading with respect to considerations of digital signalling. It is true that the CPU inside the RCX creates a logic level (1's and 0's) PWM signal intended for the (...) (19 years ago, 6-Jan-06, to lugnet.robotics)

Message is in Reply To:
  Re: mindstorms NXT
 
(...) Yeah it woulda been nice if the new one had IR as well and be able to control the "legacy" bricks. I'm sure the old ones will find a myriad of uses doing simpler jobs like moving cows heads on train layouts ;) (...) Well, I hope they are also (...) (19 years ago, 5-Jan-06, to lugnet.robotics)

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