Subject:
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RE: expansion board schematic posted
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Fri, 7 Feb 1997 18:24:20 GMT
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Original-From:
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Chuck McManis <cmcmanis@*ihatespam*freegate.net>
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Viewed:
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1615 times
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I've got one comment "balance". The expansion board adds 24 new inputs and
only 6 new outputs. Perhaps I'm atypical but I don't need any more inputs to the
handy board, I've got those aplenty, but I'm screaming for outputs to control other
parts of my robot. The servo outputs are WONDERFUL, and if I had six of them
(instead of 4) I could use the HandiBoard to control the robotic arm I've got
sitting next to it (see www.lynxmotion.com), instead I'm trying to send commands
through a bit banged serial port to a servo controller that was designed to be
talked to by a BASIC stamp.
I'm sure you saw the miniboard's "Port C" as 8 digital inputs, but I find that most
of the time I've got them all set to outputs. Sure, I've got sensors like bumpers and
optical decoders (more interrupt sources would be useful here), but often I've got
things like ultrasonics where I need to first set the sensor I want to fire (do an output)
and then sample it (do an input with an output).
Sometimes I use the motor driver circuits to turn on/off subsystems (like a video
camera transmitter) because they can handle the higher current. This was easier
on the miniboard (with its center pin) than it is on the HB but its still quite acceptable.
Anyway, this isn't meant to be a rant (even though it sounds like one perhaps) I'm
having fun with my handiboards and my current project (an "armed" tank robot :-)
uses one as the basic brains. But if you had to fix one thing that would make my
life easier, it would be many more digital outputs (at least 8, 12 would be wonderful
and 16 would be pretty much all I'd care to wish for.) If there was a way to build
24 digital-in/digital-out/analog-in/analog-out lines (where they could be programmed
by setting a register) that would be so fantastic as to make one's robotic heart
weep with joy.
--Chuck
P.S. On the two outputs, either the transistor (open collector please) the the 1A 9v
outputs would be great.
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From: Fred G. Martin[SMTP:fredm@media.mit.edu]
Sent: Thursday, February 06, 1997 9:15 PM
To: handyboard@media.mit.edu
Subject: expansion board schematic posted
Hi all,
I have put on the web site a schematic drawing of the expansion board
as it currently stands.
I would appreciate any comments regarding the feature set. In
particular, I'm not sure what's best to do with the two digital
outputs:
* just provide the raw CMOS signal
* drive an NPN transistor to give a 100 mA 5v switched power
* use a pair of transistors per output to give 1A, 9v switched power
any suggestions are welcome.
-Fred
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Message has 2 Replies:
 | | Re: expansion board schematic posted
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| It is largely a space issue, not only for chips but connectors. It definitely would be feasible to remove one of the analog muxes and substitute an output latch in its place. Then the specs would be 8 general purpose, 4 hi impedance, 4 LEGO analog (...) (28 years ago, 7-Feb-97, to lugnet.robotics.handyboard)
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