Subject:
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Re: RCX Output
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 15 Dec 1999 17:14:31 GMT
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Viewed:
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541 times
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Hi F'Amos,
I just now put a scope on the motor output ran an NQC motor test
program. At OUT_FULL the motor output is about +7V DC. At OUT_LOW
the motor output is a pulse train of 1ms 7V pulses at about 125Hz.
The low level depends on the motor load ... almost 7V with no motor
connected and approaching 0V with a stalled motor. NQC provides
seven motor speeds ... and by increasing the duty cycle of the pulse
train the average DC level to the motor is changed.
RC servos are also controlled by varying the pulse width. For most
servos a 1.5ms pulse tells the servo to go to the center position.
Increasing the PW toward 2.0ms turns the servo CW and decreasing
toward 1.0ms turns the servo CCW. The exact pulse width determines
the exact stopping position. Servos that are modified for use as
motors can never find a null position so they continue to turn
seeking the nonexistent null. Unless the PW sent to the servo is
very close to the null PW, the servo will turn at full speed. If
the null PW is 1500us, then a 1550us PW will result in a slower
speed.
Hope this helps,
- Nick -
"Avery, Amos E." wrote:
>
> --- Nick Taylor <ntaylor@iname.com> wrote:
> > If I'n not mistaken, the RCX output is pulse width
> > modulated to control motor speed, while the train controller
> > varies the DC voltage.
>
> Can anyone confirm the output characteristics of the RCX?
> It is my understanding that PWM is used to control RC servos
> and not to power them. Has anyone put a scope on the RCX's
> outputs to see what they look like? If the info is available,
> I'd be interested to know the exact output specs (eg. 0-9v 200ma).
> F'amos
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Message is in Reply To:
 | | RCX Output
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| (...) Can anyone confirm the output characteristics of the RCX? It is my understanding that PWM is used to control RC servos and not to power them. Has anyone put a scope on the RCX's outputs to see what they look like? If the info is available, I'd (...) (25 years ago, 15-Dec-99, to lugnet.robotics)
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