12 V supply to my drv8825 stepper motor driver goes down when connecting 5V from arduino

Hello guys. I'm new here. It's my first time using a drv8825 stepper motor driver for my project.
It says that you need to supply 8-45V to the VMOT and set RST and SLP to high. The problem is whenever I set my SLP pin to high, my VMOT voltage decreases (i supplied 12 V and it decreased to 2V). I can't find any other topics regarding this kind of issue. Your help would be much appreciated.

A voltage is measured between two places. Please post a circuit diagram and between which places you measure what.

I measured it here (where the arrows are indicated) using my tester.

I measured the voltage after setting my SLP pin to high. My 12 V turned to 2V

What is the rating on this 12V supply then?

Which motor type do you use (data sheet, resistance)?
What current limit did you set for the driver?

@moose04, your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with your project :wink: See About the Installation & Troubleshooting category.

What voltage did You use when setting the SLP pin (what ever that is)?

Almost certainly because the motor is drawing more current than your 12V supply is capable of giving.

I tried it without the stepper motor connected to my driver. It still decreases

The schematic diagram says that the SLP and RST pins should be connected to the 5V arduino

Its a variable power supply with 2A transformer.

I am using the NEMA17 stepper motor. The current limit i saw from its datasheet was 1.7A

NEMA only specifies the mounting dimensions of a motor, no electric values. A stepper motor will draw most current when standing still, for each coil. If you have a current controlled motor (low resistance) it can overload your PSU easily and also may burn your motor.

The data sent says

So you will need a supply capable of 4.4 Amps, not 2A.

Is that right? Because you don’t mention any voltage regulation in this. An unregulated voltage supply will be high with no load but quickly drop with a load. And anyway 2A is woefully inadequate. Unless you set the current drive on that driver to just 1A limit.
As the voltage measured on a digital multi meter can’t actually measure a high frequency square wave maybe it is not actually dropping the voltage, it just looks like that. This is because the the voltage is rapidly turned on and off to keep the current drawn to an average of what you set. This is called a chopping regulator. So maybe it is actually working and you have nothing to worry about. You need to measure the voltage on an oscilloscope to see what is happening.

There is no need to have a new post for each reply, you can simply copy and paste the questions along with your answer into one reply.

This is the recommended wiring
drv8825 pinout
The SLP signal you talk about is the SLEEP pin and wiring it high takes it out of sleep mode. In other words wiring it high turns it all on. You should never change the wiring when a circuit is powered up.

You have set the step and direction pins to be outputs in the software have you?

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