Quote:
Originally Posted by nickdigger
The resistors are arranged in something resembling an R-2R resistor ladder. I'm not terribly happy about the range and variability of the 15 input combinations, but there's enough to give me 9 usable:
Left, Down, Up, Right, Left+Right, Left+Down, Down+Up, Up+Right, and Down+Up+Right.
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I think I understand why, if you're using those resistor values you mentioned in an R-2R sort of circuit, using the internal 20 kohm (or so) pullup resistor for the pin you're going to use.
Nevertheless, I look forward to what you have come up with.
Quote:
Originally Posted by nickdigger
I sure would hate to find out that there's a $0.20 chip available to handle the button conversion (DAC?) Also, i haven't done any heat testing on a hot dashboard, to see if the values change at all. My guess is, it won't matter, because we are measuring our position on "the ladder", which should remain proportional at other temps, since the resistors will all fluctuate the same amount.
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That's part of the fun of engineering something - you get to find out what works, and what doesn't.