Re: PPMC progress

[Jon Elson <jmelson-at-artsci.wustl.edu>]

I now have all 3 axes that are supported in my versions of EMC
working from encoder input to DAC output.

The crashing problem I had is actually an old one, having
something to do with either Linux 2.0.36 or the RT patch
and the TkEMC GUI.  I have had a number of versions
of EMC later than 15-Mar-2000 that would hang up the
XFree86 screen, keyboard and mouse, or the whole
system.  I tried running the xemc GUI instead of TkEMC,
and it continued to work for about 45 minutes, until I
glitched the hardware with an errant scope probe.
Ray, do you have any ideas about this?  I'd much
prefer to stay with the TkEMC, but if it will only work
with 1999 releases of EMC, that is kind of limiting.
(I still have the debugging stuff you sent me in June, 2000,
but I'm not too sure what good it will do, as the lockups
kill the keyboard and mouse.  The caps lock key no longer
toggles the caps lock light, and the Ctrl/Alt/Backspace
won't kill X.)

I also did some testing of the interrupt response jitter,
checking the interval between DAC updates, with the
emcmod.o process running at a .001 second interval
(1 KHz).  The DAC update pulse varied by no more
than 8 uS in the entire time I watched it.  I tried doing
some mouse clicks and such, and it made no difference.
This is on a 333 MHz Pentium II.

Jon