On 9/22/2016 9:46 AM, euerka wrote:
> May I guess in this comment 320,000 KHz should be 320KHZ, is it?

Yes, sorry.  The speed required by your configuration was 320 KHz or
320,000 Hz.  My goof on the extra zeros.

> If PRU maximum pulse speed is 50KHZ, the max speed is 500? Because scale 100* 
> 500=50KHZ.

Yes, but that's the STEPGEN_MAX_VEL, you should back off that a bit
for MAX_VEL.

> I am not very sure about Schooner said "Try increasing dirhold / dirlen to 
> 1us 
> and steplen / stepspace to 5us
> If that cures it, try reducing the figures towards the chip specs until you 
> hit 
> problems"
> Anyhow I tried to change ini file, i am not sure. But it seems no affect.
> # these are in nanoseconds
>      DIRSETUP   =              1000
>      DIRHOLD    =              1000
>      STEPLEN    =              5000
>      STEPSPACE  =              5000

Those values mostly matter for FPGA based stepgen logic, or if your
PRU cycle time is very fast.  The minimum time for any of these values
is one PRU task cycle, which is typically 10 uS, or 10,000 nS, so you
probably won't see any difference by making small changes to these values.

> About speed, yes, i shift one decimal left as follow:
>      TYPE =              LINEAR
>      MAX_VELOCITY =       20.0
>      MAX_ACCELERATION =   300.0
>      # Set Stepgen max 20% higher than the axis
>      STEPGEN_MAX_VEL =    24.0
>      STEPGEN_MAX_ACC =    360.0
>          SCALE =  -100
> It works much better than before, but motor still stall when execute G00. 
> Speed 
> still too high? where to set G00 speed? 20.0 is only stand for feed speed?
> Then when motor change rotate direction, speed decrease to zero, around Zero 
> motor start move step by step, make vibration and noise. It seems it doesn't 
> work well at low speed.

MAX_VELOCITY sets the G0 speed.  20.0 should be a very reasonable
value, I run with MAX_VEL=200.0 on a system with SCALE=110.0

If your stepper is not moving well at low speed, double-check all your
wiring, the driver, and the motor itself.  Normally, stepper motors
work best at low speed and start having problems (loosing torque and
missing steps) at higher speeds.  A stepper motor _will_, however,
move with only one coil energized, but it will have problems with low
and high speeds.

Charles Steinkuehler

website: http://www.machinekit.io blog: http://blog.machinekit.io github: 
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