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Half current on idle

Posted by eslavko 
Half current on idle
February 16, 2018 03:17AM
Hello...

Is it there some way to reduce current when stepper is in idle for longer time?
I have CNC with DQxxx stepper driver and works all fine with cold motors. (they drop current to 1/2 after 0.5 second of silence in step pin)
But now I build other machine and use smoothie to control it. And after some tests motors is hot. And current is set as should be. (I did measure current if something is wrong but it's fine).
VDX
Re: Half current on idle
February 16, 2018 03:55AM
... some drivers like RAPS128 support this option - the SLP-pin (=SLeeP) will reduce (-45%) or rise (+30%) the motor current with polarity ... but the controllers has to handle this:

[www.dr-henschke.de]

Edited 1 time(s). Last edit at 02/16/2018 03:55AM by VDX.

Viktor
Re: Half current on idle
February 16, 2018 04:09AM
There are A5984 on the board. And Sleep pin just cut power to motor. So not that functionality by chip itself.
But smoothieboard has digital potentiometers to adjust current. So that can be done by software.
Just don't know if that is already done.
VDX
Re: Half current on idle
February 16, 2018 06:36AM
... No - here's the complete layout: [www.dr-henschke.de]

The SLP-pin changes the Vref between two +/- offset-values ...


Viktor
Re: Half current on idle
February 16, 2018 07:10AM
Hmm something is wrong here....
I belive this is schematic for my board but just 4 drivers are soldered...
[github.com]

And there are no manual trimmers. The current is set by digital potemtiometers from software.

VDX your schematic seems to be for some other board.
VDX
Re: Half current on idle
February 16, 2018 07:53AM
... I'm referencing a RAPS128 stepper driver - you can use this driver instead, but have to set the SLP pin by software ...


Viktor
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