On Friday 03 January 2014 13:23:04 Len Shelton did opine: > Finally got help from sourceforge with my email troubles - after 3 > months of waiting for a response. > > This homing sequence is a hot topic for me. We wrote a custom homing > configuration that works well, but unfortunately it doesn't work the the > PRU step generator. > > >> Simply give the same homing sequence number to each side. > > This wouldn't work unless you actually assigned a separate joint to each > motor and programmed your g-code accordingly. It needs to be simpler > than that. > > What our custom config does is intercepts the step signal after the > switch on that side is triggered and waits for the other side to catch > up. Then once the other side is triggered, it starts allowing the step > signal to pass back out to both sides. > > Here is the code: > > # x-axis > setp stepgen.0.position-scale [AXIS_0]SCALE > setp stepgen.0.steplen 1 > setp stepgen.0.stepspace 1 > setp stepgen.0.dirhold 35000 > setp stepgen.0.dirsetup 35000 > setp stepgen.0.maxaccel [AXIS_0]STEPGEN_MAXACCEL > net xpos-cmd axis.0.motor-pos-cmd => stepgen.0.position-cmd > net xpos-fb stepgen.0.position-fb => axis.0.motor-pos-fb > net xstep <= stepgen.0.step > net xdir <= stepgen.0.dir > net xenable axis.0.amp-enable-out => stepgen.0.enable > > # y-axis > setp stepgen.1.position-scale [AXIS_1]SCALE > setp stepgen.1.steplen 1 > setp stepgen.1.stepspace 1 > setp stepgen.1.dirhold 35000 > setp stepgen.1.dirsetup 35000 > setp stepgen.1.maxaccel [AXIS_1]STEPGEN_MAXACCEL > net ypos-cmd axis.1.motor-pos-cmd => stepgen.1.position-cmd > net ypos-fb stepgen.1.position-fb => axis.1.motor-pos-fb > net ystep <= stepgen.1.step > net ydir <= stepgen.1.dir > net yenable axis.1.amp-enable-out => stepgen.1.enable > > # z-axis > setp stepgen.2.position-scale [AXIS_2]SCALE > setp stepgen.2.steplen 1 > setp stepgen.2.stepspace 0 > setp stepgen.2.dirhold 35000 > setp stepgen.2.dirsetup 35000 > setp stepgen.2.maxaccel [AXIS_2]STEPGEN_MAXACCEL > net zpos-cmd axis.2.motor-pos-cmd => stepgen.2.position-cmd > net zpos-fb stepgen.2.position-fb => axis.2.motor-pos-fb > net zstep <= stepgen.2.step > net zdir <= stepgen.2.dir > net zenable axis.2.amp-enable-out => stepgen.2.enable > > # set all of the step signals to reset > #setp parport.0.pin-02-out-reset 1 > #setp parport.0.pin-04-out-reset 1 > #setp parport.0.pin-06-out-reset 1 > #setp parport.0.pin-08-out-reset 1 > > # invert a couple of direction signals > setp parport.0.pin-03-out-invert 1 > setp parport.0.pin-05-out-invert 1 > setp parport.0.pin-07-out-invert 1 > setp parport.0.pin-09-out-invert 1 > > # debounce the y-axis switches and connect them to signals > net switches-y1-raw <= parport.0.pin-11-in > net switches-y1-raw => debounce.0.0.in > net switches-y1 <= debounce.0.0.out > net switches-y2-raw <= parport.0.pin-12-in > net switches-y2-raw => debounce.0.1.in > net switches-y2 <= debounce.0.1.out > setp debounce.0.delay 10 > > # join the home switch signals so that both switches have to be closed > to trigger a home position > net switches-y1 => and2.0.in0 > net switches-y2 => and2.0.in1 > net home-y <= and2.0.out > net home-y => axis.1.home-sw-in > > # we will need the inverse of the home switch signals for our logic, so > run them through not gates > net switches-y1 => not.0.in > net switches-y1-inv <= not.0.out > net switches-y2 => not.1.in > net switches-y2-inv <= not.1.out > > # we will need the inverse of the direction signals for our logic, so > run it through a not gate > net ydir => not.2.in > net ydir-inv => not.2.out > > # we need to determine if the home switch for each motor is tripped > while the direction line is > # moving the motor towards the switch > > # for both y-axis motors, we will prevent the step signal from passing > to the motor > # if the motor is moving towards the switch and the switch is tripped > # so "or" the inverted direction signals and the inverted home switches > net ydir => and2.3.in0 > net switches-y1 => and2.3.in1 > net doh1 <= and2.3.out > net doh1 => not.3.in > net doh1-inv => not.3.out > > net ydir => and2.4.in0 > net switches-y2 => and2.4.in1 > net doh2 <= and2.4.out > net doh2 => not.4.in > net doh2-inv => not.4.out > > # if the step generator is trying to send a step (ystep signal) and > either the motor is moving > # away from the switch or the switch is not tripped, then pass the step > signal to the motor > net ystep and2.1.in0 > net doh1-inv and2.1.in1 > net ystep1 and2.1.out > > net ystep and2.2.in0 > net doh2-inv and2.2.in1 > net ystep2 and2.2.out > > # connect our step and direction signals to the output pins > net xstep => parport.0.pin-02-out > net xdir => parport.0.pin-03-out > net ystep1 => parport.0.pin-04-out > net ystep2 => parport.0.pin-08-out > net ydir => parport.0.pin-05-out > net ydir => parport.0.pin-09-out > net zstep => parport.0.pin-06-out > net zdir => parport.0.pin-07-out > > # we are using combined home and limit switches > # if either switch trips while the homing sequence is not running, then > triggered a negative > # limit switch fault > net switches-y1 => or2.2.in0 > net switches-y2 => or2.2.in1 > net limit-y <= or2.2.out > net limit-y => axis.1.neg-lim-sw-in > net limit-y => axis.1.pos-lim-sw-in > > net switches-x-raw => debounce.1.0.in > net switches-x <= debounce.1.0.out > net switches-x => axis.0.home-sw-in > net switches-x => axis.0.neg-lim-sw-in > net switches-x => axis.0.pos-lim-sw-in > > net switches-z-raw <= parport.0.pin-13-in > net switches-z-raw => debounce.1.1.in > net switches-z <= debounce.1.1.out > net switches-z => axis.2.home-sw-in > net switches-z => axis.2.pos-lim-sw-in# set up the other home and > limit switches > net switches-x-raw <= parport.0.pin-10-in > > >Len > > On 1/3/2014 4:45 AM, andy pugh wrote: > > On 3 January 2014 02:05, Josiah Morgan <josiahmor...@gmail.com> wrote: > >> does anyone have a script written for homing in this scenario? > > > > If the gantry can survive a momentary out-of-square then you may find > > that nothing special needs to be done. Simply give the same homing > > sequence number to each side. > > > > The problem here is that when one side id searching for the latch the > > other side might be backing off prior to searching for the latch, so > > the two sides might end up moving in opposite directions. > > > > I have wondered if the homing behaviour should be to not move any > > joint on to the next homing stage until all joints with the same > > homing sequence number have completed the prior stage, but then it > > gets a bit more complicated if you need to consider questions like > > whether the first joint to find the limit should continue in the same > > direction or should stop. (I think perhaps the answer is "stop" but > > then it is changing state without waiting, and my simple scenario no > > longer holds. > > > > If you simply use the existing home behaviour with a shared sequence > > number then the gantry will only actually be squared at the end of the > > final home move. Up to that point the out-of-square might even be > > worse. You certainly want the final move from latch to home position > > to be as short as possible.
I can certainly appreciate the thinking that went into this, Len, and thank you for posting it. But I can also see there might be room for an occasional glitch if the various addf's are not in the proper order for the whole thing to properly cascade from input pin to output pin in a single cycle. But I will say great work regardless. Thank you. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> BOFH excuse #237: Plate voltage too low on demodulator tube A pen in the hand of this president is far more dangerous than 200 million guns in the hands of law-abiding citizens. ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
