Subject:
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power and servo
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Thu, 16 Jan 1997 15:13:00 GMT
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Original-From:
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Jeffrey Marcellus <jeffreym@nortel./avoidspam/ca>
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Viewed:
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2298 times
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Hi everyone, I've got two problems that I hope your combined expertise
can solve.
1) I cut the trace connecting the the motors to the main board supply, so
that I could power them independently (as per the instructions I found on
the web). The board works fine as long as a battery is plugged into the
motor power header (in addition to the 9V system battery). However, I've
noticed that if I unplug the batteries from the motor power supply, and
take a voltage reading off the motor header, I get a reading of 2-4V.
Correct me if I'm wrong, but this doesn't seem like a good thing! I've
checked the trace to ensure it is fully cut (and the right one :-) ), but
I can't figure out where this voltage is coming from. Does anyone know
what's wrong?
2) I recently hooked up a servomotor to my handyboard. Its signal input
is plugged into pin TOC3 ( or TCO3?), and power/ground is plugged into
one of the motor outputs. I turned on the motor (fd(0);) and loaded the
servo_a5.icb routine I found on the HandyBoard site. Unfortunately, the
motor didn't respond to the init command (or any other one). I then
hooked an oscilloscope up to the signal pin, to see the output waveform.
What I saw looked like a DC offset triangular wave. This didn't change,
no matter what command I issued. I also tried hooking the servo into
Digital port 9 and loading servo_a7.icb with the same result (except the
waveform was different). I'm using the latest beta version of IC (3.10?).
Is there something I can do to find out if it's the port or the SW?
Sorry to be so verbose, but I figured the more info. I give, the easier
it will be to diagnose. Thanks in advance for your help.
Jeff
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Message has 1 Reply:
 | | Re: power and servo
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| [problem 1: voltage on motor chips when no motor voltage applied] This is normal, because the motor chip INPUTS have +5v signals on them. These signals "bleed" into the motor chip power supplies. This isn't dangerous, but it isn't particularly good (...) (28 years ago, 16-Jan-97, to lugnet.robotics.handyboard)
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