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I've been using a Pancake Bipolar Stepper Motor for a project and STSPIN220 as the driver, but I've been randomly having a lot of current issues causing my motor to jitter.

My project has been running fine for many months but out of nowhere before I even run my code, just having it plugged into my power supply while it's on will cause the motor to jitter and even while running on full step it will jitter as it goes.

I noticed that the current it's pulling has been really low compared to before. When it pulls around 0.30-0.60 A at 5V on my power supply, it will jitter, but occasionally, it will pull 0.90 A, and it will stop jittering and run smoothly.

The Vref on the driver is correct, but when I measured the current of one of the motor's coils, it was very low for a full step, even considering other factors that could be lowering it. So I raised the Vref by 50 mV, and it was working well for a while (pulling around 0.90 A), but it keeps going back to pulling 0.30-0.70 A and jittering.

I tried 2 new STSPIN220, but I get the same issues again, so I'm thinking of trying a whole different driver. I'm using a DC power supply and a voltage regulator, so I verified that the power supply is pushing 5V and the motor is receiving 3.3V. Looking at what Polulu recommends, I'm thinking of using DRV8834 as a replacement but I'm not exactly sure if it's the right fit.

Am I doing something wrong or should I just try a different driver? I included a picture of my circuit and the notes I wrote when I was trying to verify the driver in case I did anything wrong but I'm not sure anymore since it was running fine but a long time. enter image description here

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If it worked well for such a long time, and changing the driver to a new one doesn't help, then I doubt it's the problem. What comes to my mind is that the vibration from the motor caused a solder joint to break somewhere.

That would explain the erratic behavior: if it just so happens that it's making good contact, it works well for a moment, then suddenly it doesn't make good contact and it stops working as it should.

If it's the problem, then a careful look of all solder joints (using a microscope or magnifying glass ideally) should reveal the fault - assuming it's not on a hidden solder joint.

But now I see your photo and that it's not a PCB but a breadboard with jumper wires. I've personally had a lot of them break because I handled them too much. And again, depending on how you touch the wire, it may work just fine for a moment, then suddenly not. The default is not visible, so the only way to try it is to change all the wires (ideally with new ones).

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