Subject:
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HandyBoard 10-16 Servo support
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 5 May 1998 23:38:59 GMT
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Original-From:
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Max Davies <mdavies@cam.=AntiSpam=org>
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Viewed:
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1472 times
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I am trying to develop simple Hardware/Software to support up to 16 servos from
the HandyBoard.
A theoretical constraint of my plans is that only about 10 of the 16 connected
servos will be able to actively hold position at one time.
I plan to do this by multiplexing control signals for all of the servos onto one
timer output line such as TOC3 or TOC4 which are available on the expansion
port.
This requires some demultiplexing hardware, and I have a tentative schematic to
do this which uses a 73HC374 (for additional digital outs) and a 73HC154 (for
the de-multiplexing).
Being a hardware novice, my question/problem is this: the 73HC154 demultiplexor
provides "active-low" outputs in that all non-selected output lines are high
rather than low as the servo's require. To use this chip then I will have to
add 16 inverters which seems a waste.
Is there a different demultiplexor that I can use to get "active-high" outputs
to avoid the requirement of all the inverters?
Thanks,
/Max
PS: what does the HC in the middle of things like 73HC374 mean? How does it
compare to things like 73LS374? Should all components on an HB expansion board
be of the HC type?
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Message has 1 Reply:
 | | Re: HandyBoard 10-16 Servo support
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| (...) I had exactly the same problem. There is a CMOS chip by Motorola called the MC14028B that is a BCD-to-decimal or Binary-to-octal decoder. All that really matters though is that it will take a 4-bit input and decode up to *10* outputs that are (...) (27 years ago, 13-May-98, to lugnet.robotics.handyboard)
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