Two bits of news:
In the next ten days or so I'll be able to order an
Orangutan-X2. My plan is to have Orangutan-lib ported to it
as quickly as possible, and to make sure all future
development on Orangutan-lib can run on all three Orangutan
devices. This'll be fun!
The other bit of news is that after a lot of dinking around
with some Parallax QTI sensors for my line follower, I
finally figured out how the little beasties work. The
datasheet for the QTI doesn't do a great job of explaining
it. It took a fair bit of digging into the Parallax forums
before I got a good handle on things:
Basically the QTI sensor is a photoreflector that feeds a
charge integrator. The output pin of the QTI looks at the
integrator, not the sensor itself. This is not typically
how transistor-based sensors are wired up. I have my own
theory as to why Parallax did things this way, but without
tearing one apart I can't really test it.
Anyway, the post that unraveled this gave this advice for
reading a QTI:
1 - Set your sensor's I/O line to output and bring it high.
2 - Wait 0.23ms for this to discharge the QTI's capacitor.
3 - Bring the sensor's I/O line low and switch to input. At
this point the I/O line should be in tri-state mode, and
present high impedence to the QTI. Essentially the QTI's
capacitor is now isolated.
4 - Wait 0.23ms for the sensor to charge its capacitor.
5 - Read the I/O line through the ADC.
I really really wish Parallax had made this more clear in
their documentation. I wouldn't have stumbled around as
much, and I might not have even selected the QTI in the
first place. I really was after a continuous analog device.
In any case my complaints have to end here. Parallax QTI
sensors are in use on scads of robots, and they do a good
job of keeping bots in the ring and following the line. I
just wasn't using them correctly. And since I'm not using
them on a Basic Stamp, I hadn't bothered to look at the
sample code to see how they were reading them. My bad.
In any case Speedy is back on track, Orangutan-lib is still
on track, and I might even be able to build out my 4WD mini
sumo some day. Can't complain.