Sounds to me like a 74HC14 schmitt trigger would be a better solution than brute force pullups. A little square of perf board and six wires would do it.
-- Ralph ________________________________________ From: Gene Heskett [ghesk...@shentel.net] Sent: Wednesday, November 18, 2020 9:10 AM To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] couple Q's on PID's CAUTION: This email originated from outside the Walla Walla University email system. On Wednesday 18 November 2020 10:10:16 Les Newell wrote: > Hi Gene, > > Your encoder should work in the same direction as PID input. You can > reverse it by reversing the sign of the encoder scale. For example if > it is positive make it negative. > > How about a pullup on the encoder lines? > That's whats worrying me, its taking a pretty low ohmage to clean up the rise time enough to work at the motors full speed, 1500 ohms for a pullup seems rather low as its got to sink 3.4ma for a logic zero, OTOH 1500 only raises the logic zero a millivolt, not enough to see the 2nd trace separate from the first on the scope. So I laid out a pair of 1500's. Now to find a board to build it on. With the shack gone, my choices are becoming more limited as time goes by. > Les > > On 18/11/2020 15:03, Gene Heskett wrote: > > Greetings all; > > > > Working on getting the BS-1 working. > > ATM. PID.a-feedback is disconnected from from the A encoder, and > > hitting the [] keys to run the motor, the feedback from the encoder > > is the opposite sign of the PID.a input cmd. > > > > 1. Is this the correct state? Or do I need to swap encoder A/B > > leads? > > > > 2. Does anybody have a cmos buffer board I can put between the > > encoders leads and the bob's input? > > > > I have apparently damaged the encoders output stages, and hooking > > its leads up to the bobs inputs results in the rising edge of the > > signal looking like its charging a large capacitance. Falling edge > > is fine. Quadrature is excellent. > > > > However as the motor speeds up, it eventually reaches a point where > > it fails to make it to a logic 1 and the whole thing goes nuts. So I > > need the equ of a 74HCT245 to buffer it and bring it to where it can > > do a rail to rail swing. Disconnected from the bob, it does do a > > rail to rail swing with a rise or fall time in the very low > > microsecond range. > > > > Thanks all. > > > > Cheers, Gene Heskett > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Femc-users&data=04%7C01%7Cralph.stirling%40wallawalla.edu%7C1cf4607765c14f917f2308d88be4fca2%7Cd958f048e43142779c8debfb75e7aa64%7C0%7C0%7C637413162898806507%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=rJ0cWO9tXLN3%2BhelSsAVBHSmWe%2FRyYrAIizobTZYfxU%3D&reserved=0 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 <https://nam12.safelinks.protection.outlook.com/?url=http%3A%2F%2Fgeneslinuxbox.net%3A6309%2Fgene&data=04%7C01%7Cralph.stirling%40wallawalla.edu%7C1cf4607765c14f917f2308d88be4fca2%7Cd958f048e43142779c8debfb75e7aa64%7C0%7C0%7C637413162898806507%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=Pxk4XFBQ6cjoI5NEYjwzeY7zYZhIRM0iwsj6G0mklcI%3D&reserved=0> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Femc-users&data=04%7C01%7Cralph.stirling%40wallawalla.edu%7C1cf4607765c14f917f2308d88be4fca2%7Cd958f048e43142779c8debfb75e7aa64%7C0%7C0%7C637413162898806507%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=rJ0cWO9tXLN3%2BhelSsAVBHSmWe%2FRyYrAIizobTZYfxU%3D&reserved=0 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
