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Old 03-31-2011, 03:04 PM   #15 (permalink)
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Originally Posted by bobski View Post
A 5 to 1 (or thereabouts) voltage divider consisting of 2 resistors
I guess you could use the battery voltage signal as the pull-up for one of the button lines. You wouldn't be able to monitor the voltage while the button is actually being pressed, but that shouldn't be a big deal. Also, very low supply voltages (unlikely to occur) could be mistaken as a button press.
I wasn't sure if there would be spikes and noise that might be a complication if the 12v vehicle path is tied to an analog input, etc.

I'd guess the drop in voltage due to the starter would also be a gotcha. The code would probably need to detect that, to avoid false button triggers. Configuring the voltage dividers in a fairly narrow range would probably help reduce false triggers.

The more inputs that are free for pressure, temp, etc, the better.
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