On Wednesday 18 November 2020 16:49:12 Chris Albertson wrote: > If there are caps on the input. I bet the intent was to be-bounce > mechanical limit switches. Or at least to filter the switching noise > so that the frequency content is well below the software de-bounce > sampling rate. > > I've struggled with how best to de-bounce switches for a long time. > There is no best answer. RC filters are not a bad option.
I have both a .05uf capacitor to store the logic zero from the first contact when probing, right on the line to the probe input, and I use a 1 count in a debounce module for the home switch lines. Doing a fast search to get a general idea, back off 50 thou and come back at 5% of the fast speeds gets me within .0002". Good enough for the girls I used to go with. :) > On Wed, Nov 18, 2020 at 1:35 PM Gene Heskett <[email protected]> wrote: > > On Wednesday 18 November 2020 13:56:37 Gene Heskett wrote: > > > On Wednesday 18 November 2020 13:07:18 Chris Albertson wrote: > > > > That is what you do, look at the shape with no load. the 10X > > > > probe did that. > > > > > > > > I have to admit my experience with encoders is mostly wth > > > > directly connecting to microcontroller pins. No need to > > > > opto-isolate if everything is driven from the same driven power. > > > > > > > > IIt would seem then that those optical couplers are hard to > > > > drive and maybe they were designed to be driven by mechanical > > > > limit switches. In any case I don't see a reason to use an > > > > optocoupler when the device you are connecting in an optical > > > > coupler. I think if you drive the motor encoder from the same > > > > power and gund at the BOB you are good. > > > > > > Just try to buy a bob w/o them damned things. If you don't want > > > them you have to rip em out. > > > > I'll take that back. This particular Sainsmart board, the ST-V3 was > > used specifically because it doesn't have any opto's on it, but it > > still has 5 gawdawful bright leds to tally the inputs, and from the > > placement of the led's, I'd have to say they are powered by the > > logic 1 status of the input. And I'd assume that the output back to > > the 5i25 P2, is for those 5 inputs, interrupted by a 74HCT14 Schmidt > > trigger. So, the logic 1 would be anything over about 2.6 volts but > > haven't checked the data sheet for sure. So that means there is a > > pretty good load on that encoders logic 1 state if it lighting up a > > grain of sand led blindingly bright. Thinking a bit outside the box, > > I am tempted to put those 1500 ohm resistors in series with the > > inputs. I cannot find it, but every input reads 97.5 nf if I give > > the meter enough time to settle. leads open its 0.17nf. And I just > > found the 97.5nf caps that I think are the real problem. I bought > > two of these and have the 2nd one in my hands right now. I have > > several others in service here already, bought specifically because > > there's no opto's on 'em. The only bob I've found, other than the > > discoed C1G rev 4, that doesn't have them. In the morning, set up my > > hot air kit and get rid of the caps on those 2 inputs. They are > > grain of sand monolithic types on the bottom of the board. I'm > > betting that will fix it. > > > > Are Mach setups normally plagued with enough noise to need that > > filtering? > > > > [...] > > > > Cheers, Gene Heskett > > -- > > "There are four boxes to be used in defense of liberty: > > soap, ballot, jury, and ammo. Please use in that order." > > -Ed Howdershelt (Author) > > If we desire respect for the law, we must first make the law > > respectable. - Louis D. Brandeis > > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > > > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
