[Bdi4emc-help] Quickstep driver

Fri Feb 17 01:38:22 CET 2006

Hi Matt

On Thursday 16 February 2006 04:05, Matt Timmermans wrote:
> A note on setting PERIOD for the quickstep driver:   My 3.2 GHz P4 (that
> doesn't actually run any machines) likes PERIOD=7us.  The P266 laptop that
> runs my Sherline likes PERIOD=15us.  The laptop can actually run with
> PERIOD=10us, albeit slowly, so that's probably the best bet for the 1.x GHz
> class machines that are often used with EMC and steppers.

With the Celeron 433 that I use for testing, using the mini GUI, I tried 
5uSec.. Bogomips reported 66 (426 without EMC running), and KDE was very 
sluggish. Jogging the A axis could be best described as erratic - The 
parallel port is a vintage ISA card, which as we know, takes a significant 
period to write data to, so 5uSec is pushing the limits somewhat.

 Using a more realistic period of 7.5uSec (146 Bogomips), the computer is a 
lot more responsive, and rapids can quite easily hit insane levels (for a 
Sherline). Normally with freqmod, I would have gone for a conservative 20uSec 
and set the max velocities fairly low..

Going to have to dig out the scope and do some serious back to back testing 
with a few other computers, perhaps adding some additional data to /proc/emc 
to characterise the loop times a bit better. In the past, I have used freqmod 
with periods of less than 10uSec, but found jitter to be problematic... I 
have a few thoughts on tying quickstep in without duplicating the module 
init/cleanup routines to bounce of you at a later date.

Regards, Paul.

-- 
From the Klingon book of C:
Klingon function calls do not have 'parameters' - they have 'arguments' - and
they ALWAYS WIN THEM.