Filter wheel control, version 0.1
                        Radu Corlan, August 2004


This is a control program for the filter wheel, written in HC11 assembler. 
The object file (.s19) can be downloaded using the dlm20 program, which 
i have slightly modified. 

To download the program, connect a serial cable to the filter wheel 
(from COM1), put on the bootstrap mode jumper, reset the microcontroller, 
and run:

./dlm20 fwheel.s19 -ns

If the dlm20 binary does not run on your system, it can be recompiled using:

gcc -o dlm20 dlm20.c

The downloader should also compile and run under DOS, 
but i have not tested that.




    Once the program is downloaded, it is run by removing the bootstrap mode
jumper and cycling the supply. Use a terminal emulator to conect to the 
filter wheel port with 9600, 8N1, no flow control. The filter wheel does 
not echo commands, so turning  local echo might be useful. When powering up, 
the wheel will calibrate and print a status message. Then it will accept 
serial commands. The full list of commands is displayed by typing "help" 
to the wheel.

The most useful command are:

help ;-)

filter             Displays the current filter number;

filter <n>         Moves to filter number n;

fwreset            Runs the calibration routine again and stops
                   at filter #1;

in <n>             Moves focus motor one way n steps.

out <n>            Moves focus motor the other way n steps; To take out 
                   free play in the focuser mechanism, the "out"
                   command first moves "in" 10 steps, then "out"
                   10+n steps.

focus              Returns the current focus position.

All commands return either their numeric result, or the "ok" string
if successfull. Syntax errors messages consist of a '?' followed by 
the command which has caused the error. Other possible error messages
are "busy" when another command is in progress, "failed" when an error
occurs during a command or initialisation, and "bad number" which 
signifies that an argument to the "filter", "in" or "out" command is
invalid.