Hi all,
        I am now looking for a new linear position sensor for my robotics
PIC application.  I decided to leave the infrared LED to sensor link
alone because of the inherent calibration problems.  It turns out that
LEDs degrade with time to the point that constant recalibration would be
required.

        I am now exploring linear encoding for a more digital solution.
I have come across a type of absolute position linear encoding called
binary chain code which is a _non-repeating_ pattern of ones and zeros of
length 2^N.  In an N-bit code _any_ N-bit sequence appears only once in
the entire 2^N pattern so you always know where your are.

        My sensor is a Texas Instruments TSL213.  It is a 64x1 pixel
array with a simple 64-bit shift register output.  I can supposedly print my
pattern on a mylar strip and encode away. I am asking you guys if anyone has
experience with this type of position encoding especially with a PIC.  Maybe
one if you has some code written to deal with this.

Thanks,

Martin Kirk
Arizona State University
mlk@asu.edu
(602) 263-9270