Steve Blackmore wrote: > On Tue, 15 Sep 2009 20:24:16 -0500, you wrote: > > >> On Tue, 2009-09-15 at 11:06 -0400, Dave wrote: >> > > >> IMO you'd want it to be no more than a pulse wide or the threading may >> start at any of the pulses that the index spans. >> > > Strange behaviour? - It should start on either the rising or falling > edge, if it starts anywhere else it needs fixing. > This whole thread is about using the SOFTWARE enocder counter (a HAL component) for the spindle position. It is software sampling of the encoder signals, so the "rising edge" would be detected at the first sample where index was noticed to be true. But, of course, if the sample rate was slower than the quadrature count rate, the encoder counter would not be able to reliably count position anyway! So, stretching the index pulse wider than one encoder count would not actually help anything, unless you were wanting to just sense the index pulse and ignore the quadrature count.
All in all, I think the whole exercise is a big mistake. If you want to use the software encoder counter, you need a low resolution encoder, maybe as low as 25 cycles/rev, or 100 quadrature counts/rev. At 1000 RPM or 16.67 RPS, that would give 1667 counts/second, plenty safe for software counting. I would think this would still give perfectly smooth following of the axis. If you insist on a higher resolution encoder, then you should be using a hardware encoder counter. Any possibility of accidentally running the spindle at a speed where the software counter loses track will eventually occur and bite you! Jon ------------------------------------------------------------------------------ Come build with us! The BlackBerry® Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9-12, 2009. Register now! http://p.sf.net/sfu/devconf _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
