Am 23.10.2009 um 21:48 schrieb Peter C. Wallace: > On Fri, 23 Oct 2009, Chris Radek wrote: > >> Date: Fri, 23 Oct 2009 14:15:01 -0500 >> From: Chris Radek <ch...@timeguy.com> >> Reply-To: "Enhanced Machine Controller (EMC)" >> <emc-users@lists.sourceforge.net> >> To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net >> > >> Subject: Re: [Emc-users] threading Z oscillation depends on encoder >> PPR >> >> On Fri, Oct 23, 2009 at 11:33:15AM -0700, Peter C. Wallace wrote: >> >>> Its still is a quadrature decoder but it only counts on one edge >>> (rising edge >>> of A in this case, state of B on rising edge of A determines >>> direction) >> >> If this is true, it is not a correct decoding. >> >> Imagine B is high, and A goes high/low/high/low/high/low >> >> correct decoding is +1, -1, +1, -1, ... >> >> The scheme you suggest gives an incorrect +1, +1, +1, ... >> > > Well, its what I would call an up/down counter but EMC uses that > name to > describe a counter with count-up and count-down inputs. Its the > input side of > a step/direction count source. You are correct that it will not > correctly > count position on reversals so I was wrong to call it a X1 quadarture > counter... > > It should however be fine for threading. > > A true X1 counter would be easy to arrange but would have to be > another > counter mode
I'll just not that this kind of counter and a true x1 quadrature decoder dont show the same properties when fed with a signal which is not quite 50% duty cycle - this kind of counter gives stronger fluctuations in the position value than a x1 decoder since the latter only updates every full cycle, which averages out intra-cycle duty cycle errors I'll see wether I can plot it tomorrow again, it's not an issue for me since I'm done with el-cheapo encoders for good -Michael ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) 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/devconference _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
