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I'm almost ready to test the new button setup. The code is ready, i've checked input values from a breadboard; all that remains is to solder up a button board.
Hardware will consist of 4x switches, 4x 15kohm and 3x 10kohm resistors, one wire to ground, and one wire going to an analog input (with pullup enabled).
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.
Before tackling this, my intent was to keep the regular 3 assignments, and just add a 4th one off to the left for Immediate Reset of the trip2 data (which auto-resets after 7 min), and a "Down" button during parameter setup. I have since concluded i don't really need a 4th button that badly, but since it's "free", i might as well include it & rearrange things a bit.
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.
I'll post the code & jpgs in a separate thread after i verify that it works.
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