Subject:
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Re: 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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Wed, 6 May 1998 00:19:36 GMT
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Original-From:
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brian-c@!SayNoToSpam!technologist.com
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Viewed:
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1422 times
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"HC" is for CMOS chips
"LS" is for Low-Power Schottky chips
Brian Carvalho
Devry Institute
New Jersey
---- you wrote:
> 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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