Subject:
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Re: FW: 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 17:50:58 GMT
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Original-From:
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John Whitten <brat@IHATESPAMnaxs.com>
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Reply-To:
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{brat@naxs.com}StopSpam{}
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Viewed:
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3582 times
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MSI: Sean Cunningham wrote:
> I could really use that second sonar. I don't suppose there is a way
> you could design two parallel sonar connectors that are toggled with one
> of the digital outs? That way we wouldn't be taxing the handyboard
> resources except for the digital out.
Hmmm... why not do this? Use a 74273 and tie it to the HB's data lines
and strobe it with Y0 (or Y2 or Y4)? This would create a latched output
"port" at address 0x4000. Tie two of the 74273 outputs to the 'A' side
of two [N]AND gates (depending on the signal polarity- I don't use it so
I don't know :-) and then tie the SONAR signal to both of the 'B' sides.
The resulting 'C' outputs from each of the [N]ANDs would route to the
appropriate Sonar hardware. I'll attempt some bad ASCII art here.
-----\ Dn +-------+ Q0 A B
D0-D7 + ----| |------|N/AND|----<SONARIN:
-----/ | 74273 | C|-------------:SONAROUT0>
CLK | | Q1 A B
Y0 ---------| |------|N/AND|----<SONARIN:
+-------+ C|-------------:SONAROUT1>
SONAR--------:SONARIN>
This is of course assuming that the SONAR signal from the HB is digital.
If its analog you could substitute a 4016 bilateral (analog) switch IC
which would accomplish the same thing. Just use the switch's GATE
instead of 'A'.
The beauty of this approach is that you also get 6 additional latched
output bits for FREE!!! And as the discussion here has recently
indicated, EVERYONE would like MORE OUTPUTS PLEASE!!! :-) (Since I'm
cc'ing this to the HBlist I just thought I'd cast my vote :-)
If you want to set up another input port, you could use a 74373 or 74374
(depending on whether or not you wanted level-triggered or
edge-triggered inputs) and wire it up to Y1, Y3, or Y5.
Anyway, I hope this helps you or somebody on the list!
Cheers
John Whitten
brat@naxs.com
--
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Message is in Reply To:
 | | FW: expansion board schematic posted
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| I'd agree with this option - I don't need any more inputs, but I do need 4 logical outputs 2-4 Hi-current outputs Serial communications 1 (preferably 2) sonar connectors I could really use that second sonar. I don't suppose there is a way you could (...) (30 years ago, 8-Feb-97, to lugnet.robotics.handyboard)
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