The jitter is due to dirty analog hardware. Pots inside the wheel for
example. Eliminate it by cleaning them, or even replace them.
Or get a wheel with optical pots (MSFF for example).
Yes, PDPI doesn't use the regular hardware joystick interface, so it
in fact works only through Direct Input. The special driver talks to
the PDPI card in a different way than to a normal joystick. I.e. it
just reads out digital values that are snapshots of what the card
thinks the state is.
Older analog joystick methods are timing the time it takes to get a
potentiometer or something to fill up or zero down. Which takes time.
(I don't know the real technical details). The PDPI does that in the
background, leaving only ready-to-read values for the Direct Input
driver.
Ruud van Gaal
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