To All,

    I am submitting this into the public domain in the hopes that it might
be useful to someone trying to build their own CNC controller.

	This is a translator for 2 unipolar stepper motors with direction, step
per motor and full or half-step using the PIC16F84 PIC.

    I wrote the JSTEP software as a way of getting used to the various aspects
of using and controlling stepper motors, using the PIC16F84 and the freeware
JAL compiler that was created for the PIC micro. I got the original idea from
a program called STEP.ASM from DAK Engineering (Maker of TURBO-CNC) and I
wondered if I could do the same in JAL. I added support for full and half
stepping, as STEP.ASM suggested, by looking at the pin a4. The program is
table driven for speed. Best-case execution is about 25 clock cycles and
worst case is about 75 clock cycles. At 400nSec that's 10uSec best case
loop time and 30uSec worst-case loop time. If you have a 50% duty of 30uSec
up and 30uSec down then this is about 16,666Hz max input frequency, or around
10,000rpm in full step mode and 5,000rpm in half step mode for a 100 count per
rev. stepper motor. (In Theory)

    The files include the following:

    JSTEP.JAL    - My original JAL source code.
    JSTEP20I.HEX - A 20MZ, inverted output version.
    JSTEP20N.HEX - A 20MZ, non-inverted output version.
    JSTEP10I.HEX - A 10MZ, inverted output version.
    JSTEP10N.HEX - A 10MZ, non-inverted output version.
    JSTEP4I.HEX  - A 4MZ, inverted output version.
    JSTEP4N.HEX  - A 4MZ, non-inverted output version.

    I could only test it with two small Howard 12V, 600 gram, motors and a
555 timer as the pulse stream source. I tested it up to about 400pps before
I started dropping steps. This looks to be more of a problem with my power
supply and motor and not having an acceleration table then the translator
program itself. In any case I hope that it lives up to my expectations.

    As always, please use this program a your own risk.


                        Best Regards

                        David Q. R. Wagoner