Position Controller
TESTING OUT THE POSITION CONTROLLER.
our toolbox, our MacGyver sense tingled when we found a
glue stick. Of course, we weren’t going to use it to glue the
encoder wheel onto the Scribbler (it wasn’t a diorama for
our grade school class anyway), but it just so happened
that the lip of the encoder wheel fit perfectly into the glue
stick cap. We chopped off an end of the cap, super glued it
to the Scribbler’s right wheel, and we were ready for
encoding.
We were ready for coding the encoder after we
attached the position controller itself. The module comes
with some 3/16” Phillips flathead screws for attachment.
While something a bit more stable and substantial would
have been better, we opted for a quick cardboard mount
that gave more than enough support for the light module.
The spacing of the optical interrupter switches was not too
unforgiving, and we were ready to program the Scribbler.
Better Know A Syntax
IMPLEMENTING THE ENCODER.
however, may be a bit intimidating for tinkerers not sure
where to start.
The Scribbler has also anticipated the needs of
programming neophytes, and available on the Scribbler
page is a very accessibly written guide to writing your first
Basic programs. The guide shepherds beginning
programmers from the essentials of compiler directives and
a variation on the classic Hello World exercise, all the way
to program loops and logical operators. The page for the
position controller includes a sample program for
interfacing the unit with an HB- 25 motor controller, and
after the solid introduction with the Scribbler, even
beginners should be able to understand the motor
controlling code.
While the Scribbler documentation provides an
excellent first step into Basic, we think that the position
controller is a great way to really test the understanding of
new programmers. The position controller presents a
programming problem where the intuitive physical
understanding of how the device works should help even
those without a formal education in programming or
WRITING A DEAD RECKONING PROGRAM IN THE BASIC STAMP EDITOR.
The Scribbler comes with an easy-to-use graphical programming interface,
and while many casual members of the
SERVO Nation may be content with the
intuitive graphics, we think that the
position controller is also a great way to
initiate novice programmers into the
world of Basic programming. As Part
One of our 100 part series, today we
introduce Basic – the fightin’ Basic!
The Scribbler is outfitted with a
BASIC Stamp 2 microcontroller, and up-to-date versions of the BASIC Stamp
Editor are available on the Parallax
website — along with voluminous
documentation on programming in
Basic and the microcontroller itself. The
highly technical documentation,
SERVO 07.2010 73
