Re: CNC PRO

In a message dated 7/1/99 9:21:03 AM Eastern Daylight Time, dmauch@...
writes:

<< >Probably going to give this a try.

>For an outside opinion, what do you think of his use of the timing chip
>on the motherboard to time stepper pulses as opposed to using timing
>loops in software? Could this be of any real world advantage, or is it
>just a different approach?

We'll it would be different but its easier to to do it with software and
with all the variety of computers and compuuter speeds I don't think it
would be practical.

>>

I've done a little programming making use of the onboard timer(s) on a PC.
AFAIK, all PC's have a 1.19318 MHz crystal controlled clock on board. The
counter chip has three channels, one of which (channel 0) can be reprogammed
without upsetting too much in the computer. Channel 1 controls DRAM refresh
and should _not_ be messed with. There is a 32 bit counter incremented by the
bios in low memory (at location 0040:006C) that can be used for timing also..

I have some assembly language source code that can read the various counters
and will act as a 32 bit up-counter that runs at 1.19318 MHz...

Jon Croad