Re: [CAD_CAM_EDM_DRO] EMC Lathe mode.

> No, completely wrong, assuming you are hooked to an encoder counter.
> In between pulses, you have no idea what part of the revolution you are

Jon:
But the software is always interrupting at 8192 hz, unless the spindle is
turning faster than about 60,000RPM wouldn't it simply be a case of timing
the revolution to see how many 122uS periods it takes from Pulse to pulse to
know exactly where it is? at 4000RPM, one turn is 66 turns per second, so
one revolution would be 15ms, so 124 interrupts will occur during that one
turn (and 4000RPM would be very fast for most threading wouldn't it?).
So if a program saw the index pulse happen, it could then pick any of 124
start points to start a thread run, this would be very repeatable (to the
122uS point or so, but could also be timed from interrupt to make it
accurate to the nS if a person wished. Or am I missing something obvious? It
seems to me that one pulse per revolution should be enough that I could time
a theoretical start point to be accurate to a very small percentage of
error. At low speeds, like 500RPM, I would have 983 interrupts happening
between pulses. So if I want to start a thread 1/4 of a revolution from zero
point, I would just skip 245 interrupts doing nothing and then time from
interrupt number 245 for 91.5uS and begin the thread run. This should be
EXACTLY 1/4 of a revolution of a spindle going at 500RPM. Sorry if I'm
missing something here, sometimes the obvious flys right over my head.

Art
Master5 Software
http://users.andara.com/~fenerty/master.htm