Noise with two pcs of DRV8825

Hi,

I am driving two different steppers with two pieces of your pololu.com/product/2133 driver.

When i am driving only one at a time, everything is ok, but when i am driving two motors (one with 1.7A and one with 0.6A), there is some additional noise beside the normal humming noise, like some kind of “sssss” and variations of it. it also happens when the motors are stalled. when i disconnect one, the noise suddenly stops. i think there must be some interferences or electrical noise somewhere. i found out, that it sometimes stops, e.g. when the motors are in holding position and a pull the decay-mode pin of the ic to ground. but that doesn’t work every time. maybe it depends on the position of the motor.

can you give me some hints how to minimize such kind of noise? maybe some additional capacitors somewhere?

Hello.

Can you tell me more about your setup? What are you using to send step commands? How you are supplying power? Can you take a video (with audio) so we can hear the noise? You might try adjusting the current limit on your drivers, or raising the supply voltage to see if it changes anything.

-Jon

hello john,

[quote=“JonathanKosh”]Hello.

Can you tell me more about your setup? What are you using to send step commands? How you are supplying power? Can you take a video (with audio) so we can hear the noise? You might try adjusting the current limit on your drivers, or raising the supply voltage to see if it changes anything.

-Jon[/quote]

i am not sure if a video could demonstrate this sound. it is not very loud but a little disturbing. a have a switching power supply like this one[url title=“this one”]http://www.aliexpress.com/item/DC-LED-Power-Supply-Charger-Transformer-Adapter-12V-6A-110V-220V-to-12V-For-RGB-LED/1902339053.html/url]. maybe there are some interferences? do you think, it would help plugging in some higher elkos, e.g. 100µ/50V between GND and VDD on the stepper driver? at the moment i have a 47uF 25V there…

what about the cable diameter? at the moment i use a relatively thin dupont-connector for the power supply. does it make sense using a thicker cable?

I do not think the noise is caused by a supply like that, but you might try others to see if the noise differs. Have you tried lowering the current limit or raising the supply voltage like I mentioned earlier?

-Jon