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- SOLVED: Tuning stepper motor with Gecko 201 driver
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SOLVED: Tuning stepper motor with Gecko 201 driver
21 Dec 2013 05:16 #41886
by mtngun
Replied by mtngun on topic Tuning stepper motor with Gecko 201 driver
UPDATE: I switched back to the #1 HP DC5000, replaced 10.04 with 8.04, and upgraded to 2.5.3.
-- now box #1 runs pins 14 & 16.
Those pins refused to work at all with 10.04.
-- now box #1 runs the Gecko 201 beautifully, even smoother than the other box (this box has lower latency).![:) :)](/media/kunena/emoticons/smile.png)
So I'm going to declare this problem solved.![:woohoo: :woohoo:](/media/kunena/emoticons/w00t.png)
It appears there is either a bug in 10.04 or else 10.04 is not compatible with my box. 10.04 did not like pins 14&16 and 10.04 did not like the Gecko 201.
Is there a bug report somewhere where I should report this?
-- now box #1 runs pins 14 & 16.
![:) :)](/media/kunena/emoticons/smile.png)
-- now box #1 runs the Gecko 201 beautifully, even smoother than the other box (this box has lower latency).
![:) :)](/media/kunena/emoticons/smile.png)
So I'm going to declare this problem solved.
![:woohoo: :woohoo:](/media/kunena/emoticons/w00t.png)
It appears there is either a bug in 10.04 or else 10.04 is not compatible with my box. 10.04 did not like pins 14&16 and 10.04 did not like the Gecko 201.
Is there a bug report somewhere where I should report this?
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21 Dec 2013 07:30 #41893
by andypugh
A step length of 1 and a step space of 0 makes sense in the context of a "doublestep" config. It means "turn the pin on this cycle, and "reset" will turn it off again in reset-time nS. This only makes sense if the step length is a lot less than the base period, and if the step-length + step space is a bit shorter than the base period.
I am wondering if your base period simply isn't long enough to fit in the step-space that is needed (5uS is a pretty long step space, though a lot less than your base period.
If there is documentation there which says that the timings are in base periods, then it needs to be found and altered. The definitive description of stepgen is here:
www.linuxcnc.org/docs/html/man/man9/stepgen.9.html
Incidentally, the choice of software _can't_ have any effect on the sensitivity of the hardware to VFD interference. Once the registers are set to put the pins high or low then everything downstream is identical between LinuxCNC and TurboCNC. (Assuming the hardware is exactly the same, which I am no longer sure about)
Replied by andypugh on topic Tuning stepper motor with Gecko 201 driver
Andypugh, I'll try setting the steplength and space to 20,000 as you suggest but ...... I'm not sure that it is meaningful. In one place the documentation says those settings are in nanoseconds and in another place it says it is in base periods. So a steplen = 1 would be one base period (the base period is 67,000 on my 8.04 box). If that is true then setting the steplen timing to 20,000 in StepConf would have no effect. This seems to be the way it works because no matter what you plug in for step timing in StepConf, the HAL steplen is always 1
A step length of 1 and a step space of 0 makes sense in the context of a "doublestep" config. It means "turn the pin on this cycle, and "reset" will turn it off again in reset-time nS. This only makes sense if the step length is a lot less than the base period, and if the step-length + step space is a bit shorter than the base period.
I am wondering if your base period simply isn't long enough to fit in the step-space that is needed (5uS is a pretty long step space, though a lot less than your base period.
If there is documentation there which says that the timings are in base periods, then it needs to be found and altered. The definitive description of stepgen is here:
www.linuxcnc.org/docs/html/man/man9/stepgen.9.html
Incidentally, the choice of software _can't_ have any effect on the sensitivity of the hardware to VFD interference. Once the registers are set to put the pins high or low then everything downstream is identical between LinuxCNC and TurboCNC. (Assuming the hardware is exactly the same, which I am no longer sure about)
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22 Dec 2013 00:20 #41907
by mtngun
The StepConf wizard asks for timing in nanoseconds, yet no matter what I input for "Step Time," (typically 500 nanoseconds for Geckos) the generated HAL file "steplen" is only "1". So if the manual is right about nanoseconds, then the Wizard is doing it wrong. They both can't be right.
10.04 was definitely doing something weird to the parallel port. My stepper problems went away when I switched to 8.04 with no other changes.
The steppers are running great in 8.04 now. My challenge turns to learning how to get around in the LinuxCNC interface.
Replied by mtngun on topic Tuning stepper motor with Gecko 201 driver
This Wiki page talks about how Steplen is in base periods. wiki.linuxcnc.org/cgi-bin/wiki.pl?Tweaki...ftwareStepGenerationIf there is documentation there which says that the timings are in base periods, then it needs to be found and altered.
The StepConf wizard asks for timing in nanoseconds, yet no matter what I input for "Step Time," (typically 500 nanoseconds for Geckos) the generated HAL file "steplen" is only "1". So if the manual is right about nanoseconds, then the Wizard is doing it wrong. They both can't be right.
10.04 was definitely doing something weird to the parallel port. My stepper problems went away when I switched to 8.04 with no other changes.
The steppers are running great in 8.04 now. My challenge turns to learning how to get around in the LinuxCNC interface.
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22 Dec 2013 04:42 #41916
by andypugh
Stepconf typically creates a "doublestep" config where the step-length is actually set by the parport reset-time (which, you will see, in in nS)
The "1" of step and "0" for space are simply to ensure that stepgen doesn't try to re-zero the pin on the next iteration.
If you were to set you step + space to a time longer than the base thread period I would expect to see it switch methods.
Replied by andypugh on topic Tuning stepper motor with Gecko 201 driver
The StepConf wizard asks for timing in nanoseconds, yet no matter what I input for "Step Time," (typically 500 nanoseconds for Geckos) the generated HAL file "steplen" is only "1". So if the manual is right about nanoseconds, then the Wizard is doing it wrong. They both can't be right.
Stepconf typically creates a "doublestep" config where the step-length is actually set by the parport reset-time (which, you will see, in in nS)
The "1" of step and "0" for space are simply to ensure that stepgen doesn't try to re-zero the pin on the next iteration.
If you were to set you step + space to a time longer than the base thread period I would expect to see it switch methods.
The following user(s) said Thank You: mtngun
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23 Dec 2013 01:39 #41932
by mtngun
Replied by mtngun on topic Tuning stepper motor with Gecko 201 driver
That makes sense now that you have explained it that way.Stepconf typically creates a "doublestep" config where the step-length is actually set by the parport reset-time (which, you will see, in in nS)
![:) :)](/media/kunena/emoticons/smile.png)
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- Configuring LinuxCNC
- Configuration Tools
- StepConf Wizard
- SOLVED: Tuning stepper motor with Gecko 201 driver
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