There is a electrical scheme of my board:

Electrical scheme

That's what I see on output, when stepper motor is not connected / is connected:

With_eng Without_eng

The stepper motor doesn't move and produces a squeaking sound and vibration, but I feel torque a little bit on stepper motor. Can't figure out what's wrong.

V motor is 12V, VREF = ~1.1V. Stepper motor 17HS4401.

There is a PCB layout:

PCB layout Top layer PCB layout bottom layer

UPD: Now I put the driver on breakout board and repeated Polulu scheme. Still didn't succeed.

This oscillogram is for STEP pin of DRV8825: STEP pulse duration HIGH and LOW are both more than 3us


This is for R10 and R11 (mean amplitude is near to 100mV):


enter image description here

  • \$\begingroup\$ You possibly have the step sequence wrong.. \$\endgroup\$ – 12Lappie Oct 9 '17 at 15:06
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    \$\begingroup\$ Also, you might provide a link or datasheet for the motor you are using and tell us how you have the coils connected. Is the lower image captured on the same sweep setting as the upper image (and with the same step rate)? \$\endgroup\$ – Tut Oct 9 '17 at 15:33
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    \$\begingroup\$ "Current limitation is correct, coil connection is correct."" R26 is 20 kOhm" ... I guess if you are going to skirt around the questions as asked, you are on your own. Good luck. \$\endgroup\$ – Tut Oct 9 '17 at 17:16
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    \$\begingroup\$ @GAttuso there's nothing wrong with that connection. It's also used on the Pololu breakout board. Basically in the event of a fault it puts the chip to sleep. However if the sleep pin is driven from the AVR, the connection does nothing. \$\endgroup\$ – Tom Carpenter Oct 25 '17 at 19:58
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    \$\begingroup\$ PCB layout would be useful to see also. \$\endgroup\$ – Tom Carpenter Oct 25 '17 at 20:00

Remember that you are using the IC outside the datasheet suggestions.

enter image description here

Where with a more degraded accuracy, where already between 15% to 25% nominally, you can confuse the controller, considering the relatively low current setting (which seems to be to 1.6A according to the comments). This heavily depends on how is made the layout, as well as any interference with the control IC itself if not even EMI withint the MCU itself, mismatching some control signals. With Atmel parts and huge EMI from motors, this could temporary brick the MCU.

A bit more on your scope screes. Also when the driver is actually output power, it generates a proper signal according to the input squarewave. So what you see (and we don't because the scope time division is too large in your picture) is probably the controller struggling with something. When is not connected to a motor, it is very likely that the output will be simply following the input.

So to finish, to know what actually is going on here, you shall at least: check the mode pins, make the stepper working with a reference within proper values, provide windings characteristics (stepper's datasheet) and, last but not least, a zoom of the oscilloscope capture when the motor is producing the squeaking sound.

  • \$\begingroup\$ Current mode pins configuration: RESET - High, SLEEP - High, ENABLE - Low, M0 - Low, M1 - Low, M2 - Low, DIR - Low. Engine datasheet. Oscillograms was updated in OP. "make the stepper working with a reference within proper values" - I do not quite understand what I need to do. If we are talking about V3P3OUT and R26, now I have 10kOhm trimmer instead of 20 kOhm, and current limit is now set to 0.5 A. \$\endgroup\$ – A. Shirkov Oct 26 '17 at 10:35
  • \$\begingroup\$ @A. Shirkov R10 and R11 on PCB layout must be directly and closely connected to GND of the U5. Please add scope shot on STEP of the U5, R10, R11. \$\endgroup\$ – AltAir Oct 26 '17 at 12:33
  • \$\begingroup\$ OP was updated. On R10 and R11 I do not see anything as I expected (btw the voltage drop on this resistors is insignificantly small). \$\endgroup\$ – A. Shirkov Oct 26 '17 at 14:19
  • \$\begingroup\$ @A. Shirkov you must change the Volt/DIV for the CH1 of the oscilloscope for small signal. \$\endgroup\$ – AltAir Oct 26 '17 at 15:16
  • \$\begingroup\$ Try to apply a <1kHz signal to STEP pin and see if something happens. What I see seems glitch of 8V on 5V logic, so try also to protect the pin. R26 is not important, I need to know what is the voltage out of the trim R26 and not its resistor value. But if 0.5A is correct, you are providing 0.25V of reference, where the minimum advised is 1V. \$\endgroup\$ – thexeno Oct 27 '17 at 0:02

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