On Thu, 19 Mar 2020, Gene Heskett wrote:
Date: Thu, 19 Mar 2020 18:41:42 -0400 From: Gene Heskett <[email protected]> Reply-To: "Enhanced Machine Controller (EMC)" <[email protected]> To: [email protected] Subject: Re: [Emc-users] A hal question?On Thursday 19 March 2020 17:27:55 Peter C. Wallace wrote:On Thu, 19 Mar 2020, Gene Heskett wrote:Date: Thu, 19 Mar 2020 17:02:59 -0400 From: Gene Heskett <[email protected]> Reply-To: "Enhanced Machine Controller (EMC)" <[email protected]> To: [email protected] Subject: [Emc-users] A hal question? Greetings; I am trying to reduce the f/r error in an ATS667 based encoder. The index pulse is turned upside down by a reversal of spindel direction. Tts the nature of the beast to remain in this stable state until the approach of the triggering ferrous metal causes the first reversal which the edge ignores, and then goes back true or false as the ferrous piece crosses the center. So I break into the index signal path with a comp looking at the velocity to generate an nearly instant direction signal and use it to diddle an xor which will restore the upside down index signal to same side up, this is then fed to an edge detector which fires on the positive going edge, giving a consistent to the degree reset back to the encoder regardless of spindle direction. Does anyone see any problems with that? The reversal of the pulse at the spindle reverse point should become the out of time and possible way early pulse that sets it up to actually trigger as the piece crosses the center of the ATS667. According to my thinking anyway. Poke it full of holes if I'm wrong.No index patching is needed as the index is only looked at when going in one directionwhich I would naturally define as a + output at velocity-out? The text reads like it resets the counter to zero everytime this index pulse goes true, although that isn't stated, could be false. Confusing to be sure, so which edge is the active edge when waiting to start a G76 or G33.1? rising or falling? the first edge as the index piece is approaching could have have some timing error, while the 2nd edge as the pole piece crosses the centerline of the hall elements should be pretty accurate.
At the FPGA pin the default index polarity is falling edge (but you can change this with the index_invert pin)
Thank you Peter. Stay safe now.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-usersPeter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-usersCheers, 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
Peter Wallace
Mesa Electronics
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