The main reason why I’m not able to get it working out of the box is the Teknic motor stops being in homing mode if the machine is jogged at all after the enable pin is asserted. So I would like the enable pin to be a part of the homing sequence itself, to avoid any issues arising from that.
I left out that I’ll need a homing sequence for a continuous rotary axis, as well. The Teknic motors can also very accurately home to a specific angle when enabled. We’ll have a 50:1 reducer on the motor, so it could feasibly home to 50 different locations without first moving to a limit switch. Because of that the motor must be enabled twice during the sequence (the first in order to command it until the limit switch is found, the second to accurately home to an angle once found). I plan on starting with the linear axes to see if I can learn anything helpful prior to starting on this more involved routine. It seems that in order to avoid a custom build of MachineKit, that I need a way to either trigger immediate homing or the ability to detect that a user initiated immediate homing from within HAL. Any ideas? John Allwine Owner of Allwine Designs https://www.allwinedesigns.com > On Feb 22, 2020, at 11:25 AM, Bas de Bruijn <b...@basdebruijn.com> wrote: > > > The google group fell off the reply. > For completeness done manually :) > >>> On 22 Feb 2020, at 17:44, Bas de Bruijn <b...@basdebruijn.com> wrote: >>> >> >> >> >>>> On 22 Feb 2020, at 15:25, John Allwine <j...@allwinedesigns.com> wrote: >>>> >>> Hi Bas, >>> >>> Thanks for your suggestion! I’ll definitely look into writing a custom >>> component rather than a custom MachineKit build. >>> >>> I’m afraid, though, that I don’t completely follow the rest of your >>> suggestion. Could you please expand a little? I have used immediate mode >>> before. Let’s say a user clicks a home button in the Axis GUI. How could I >>> tie into that event to start the process? Alternatively, if I created my >>> own button to trigger something in Hal, how would I trigger immediate >>> homing? How would you recommend setting the position on the rising edge? >> >> You might not have to do anything. I’m not an expert on the cnc stack. >> If you have wired the enable pin of the motor physically and in HAL to the >> enable pin of the motion component, then pressing the home button in the GUI >> should start homing. Thus moving towards the end of your guide/motor. >> Make sure you wire the smart pin to the home Hal pin. >> Would that not work out of the box? >> Does the special pin stay high after homing? >> >>> >>> I believe I have a good grasp on how Hal works, but my knowledge of the >>> built in components is limited. >>> >>> Thanks again for the help! >>> >>> John Allwine >>> Owner of Allwine Designs >>> https://www.allwinedesigns.com >>> >>>>> On Feb 22, 2020, at 1:04 AM, Bas de Bruijn <b...@basdebruijn.com> wrote: >>>>> >>>> >>>> >>>> >>>>>> On 21 Feb 2020, at 23:30, John Allwine <j...@allwinedesigns.com> wrote: >>>>>> >>>>> >>>>> I'm looking into using Teknic SDSK servo motors with MachineKit. The SDSK >>>>> models accept step and direction pulses like a stepper motor, so using >>>>> hal_pru_generic's stepgen is straight forward. The major issue I see is >>>>> attempting to use Teknic's precision homing routines, as it doesn't fit >>>>> into MachineKit's limit switch routines. I'd really like to use their >>>>> homing routine because it is accurate to less than 1/10,000 of an inch in >>>>> my setup, which could be difficult to achieve using my own limit switch >>>>> setup. It seems to me that in order to do so would require either a >>>>> custom homing routine implemented in C++ (so a custom build of >>>>> MachineKit). Any thoughts on this would be appreciated! >>>>> >>>>> The Teknic motors have 3 control pins and 1 feedback pin: >>>>> >>>>> Control Pins: >>>>> Enable - Used to enable/disable the motor and plays a part in initiating >>>>> the precision homing (see below). >>>>> Step - Same as for a stepper motor >>>>> Direction - Same as for a stepper motor >>>>> >>>>> Feedback - They refer to this as the HLFB (high level feedback) pin. Can >>>>> be set to a number of different options, but the relevant one for homing >>>>> would be ASG (all systems go) Position, which is high when the motor is >>>>> in the commanded position, low while moving. >>>>> >>>>> The precision homing sequence is initiated as follows: >>>>> >>>>> 1) Put the motor into homing mode by toggling the enable pin on (if it's >>>>> already on, then turn it off, then back on). >>>>> 2) Command the motor with step and direction to move the joint to a hard >>>>> stop. >>>>> 3) The motor will detect the hard stop and stop accepting step pulses >>>>> until it is commanded to go the opposite direction. >>>>> 4) After the hard stop is detected the motor will back off to a precise >>>>> location a configured number of internal encoder counts away. >>>>> 5) After a configured number of milliseconds (default is 10), the HLFB >>>>> pin asserts indicating that homing is complete. >>>>> >>>>> The hard stop detection and precision homing is fantastic. After the >>>>> first homing sequence, the motor will return to a very precise location >>>>> as long as the hard stop stays within ~2mm. I can physically put a shim >>>>> (less than 2mm thick) in front of the hard stop and it still goes to a >>>>> precise location that properly ignores the shim (so wearing on the hard >>>>> stop over time doesn't affect the precision of the homing sequence). >>>>> >>>>> So, does anyone have recommendations for how to perform this sequence >>>>> properly in MachineKit? Preferably, I'd avoid needing a custom build of >>>>> MachineKit, but if it's required to make homing a simple click of a >>>>> button then I'll have to go that route. >>>> >>>> Hi John, >>>> >>>> So if I understand correctly your homing sequence is started on the rising >>>> edge of the enable pin. >>>> >>>> Then you need to move to your chosen homing side. >>>> Your homing is done when the special pin rises. >>>> >>>> Maybe all parts are already there. >>>> Have you tried configuring as ‘immediate’ homing? So rising special pin >>>> sets the position? >>>> http://www.machinekit.io/docs/config/ini_homing/ >>>> >>>> Even if you decide you need a special component, you do not have to >>>> rebuild MK, just write the comp in C and install with instcomp. >>>> >>>> http://www.machinekit.io/docs/hal/instcomp/ >>>> >>>> Best, >>>> Bas >>>> >>>> >>>>> -- >>>>> website: http://www.machinekit.io blog: http://blog.machinekit.io github: >>>>> https://github.com/machinekit >>>>> --- >>>>> You received this message because you are subscribed to the Google Groups >>>>> "Machinekit" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send an >>>>> email to machinekit+unsubscr...@googlegroups.com. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/machinekit/6b01a405-251f-4633-af72-abbcd6c78ab0%40googlegroups.com. >>> >>> -- >>> website: http://www.machinekit.io blog: http://blog.machinekit.io github: >>> https://github.com/machinekit >>> --- >>> You received this message because you are subscribed to the Google Groups >>> "Machinekit" group. >>> To unsubscribe from this group and stop receiving emails from it, send an >>> email to machinekit+unsubscr...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/machinekit/7E019B91-0888-4BE4-8F65-1F22B40EC7C6%40allwinedesigns.com. -- website: http://www.machinekit.io blog: http://blog.machinekit.io github: https://github.com/machinekit --- You received this message because you are subscribed to the Google Groups "Machinekit" group. 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