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From: firstname.lastname@example.org (Peter Jeffe)
Subject: Re: translate input resistance to output resistance
Date: 14 Nov 2002 18:02:09 -0800
NNTP-Posting-Date: 15 Nov 2002 02:02:09 GMT
Tony Williams wrote in message news:<email@example.com>...
> > Input Ohms Output Ohms
> > 82 23870
> > 164 17030
> 284 2223 <-- Is that value correct?
> > 464 12270
> > 794 8950
> > 1474 6730
> That's a 6-bit i/o, 64 possible states from each
> switch-array. You should really sit down and fully
> map each array.... all 64 combinations per.
> There could be a mathematical relationship, for
> example it has the slight sniff that maybe the Input
> Ohms is a parallel switched resistor array, whereas
> the Output Ohms could be a series resistor array. In
> which case it could be as straightforward as six
> comparators driving six OptoFETS. But any such
> possibility cannot be seen until a full map is done.
I guess I'm not being very clear--there is definitely no relationship
between the input and output because they are from/to two unrelated
devices: a Saab steering-wheel control and a Sony head unit. Further,
I am choosing which buttons on the steering wheel to map to which
functions on the head unit. So the mapping and values are totally
arbitrary. That's why there's no pattern there at all.
> > ..... I agree with Phil that a microcontroller would give me a
> > lot of flexibility, but I also agree that it's a bit more work than I
> > had hoped for (and this is definitely a one-off application).
> However, total flexibility needs the brute force of
> a lookup table, which does imply some means of storing
> 64x random 6-bit numbers, be it EPROM or microcontroller.
I guess I was hoping that I could just use a circuit with something
like 6 electronic switches in parallel, each of which would only
"close" when its particular resistance/voltage was seen (corresponding
to its button), and which would then generate the appropriate output
resistance/voltage. Is there really nothing like this?
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