Thread: Resistance to Analog Input Value.
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Unread 15-04-2003, 16:12
Lloyd Burns Lloyd Burns is offline
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FRC #1246 (Agincourt Robotics)
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Join Date: Jun 2001
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A little late...
One thing to remember is that the analog inputs are different on the OI and the RC. RC = voltage input, OI = charging current from +5V to the input.

The RC is as described in this thread, but the OI essentially measures resistance from +5V to the analog input, by measuring the time it takes to charge a known capacitance over a given voltage change, through the resistance.

This is becasue they can then use joysticks --- the same way that the Apple II, ][+, //e, //c and all did in the early 1980's, and similar to the IBM PC and PCJr of the same era.

I did a check on the then current '98 control system, with a ten turn pot going into both types (at different times), and reading the debug values at various positions of the correctly wired pot.. The was a small nonlinearity with the OI. I have not done it with the black boxes, to see if IFI has improved the sytem.