Hello,
I am new to these drivers so I have read the guides and watched the video, but I am having trouble with setting the current on my DRV8825. I am at the point where I have tried to remove anything not needed to try and get proper readings on the VREF pin so I am using 2 bench power supplies, one set to 5v (emulating micro-controller power) one set to 12v (emulating motor power).
I am connecting Sleep and Reset to 5v POS, and GND (bottom right GND in Diags) to 5v NEG
I am connecting VMOT to 12v POS, and GND (one below VMOT/top right) to 12v NEG
Should this be the correct bare minimum setup to use the VREF pin adjust the Current limit with the formular VREF x2 = Current Limit?
Or am I missing something?
Hoping someone can just verify I got whats needed for a proper vref test as the voltage on my unit is 4.x volts at the vref and it does range up and down a little bit with the pot but only a few millivolts. Am I doing it wrong or is it a defective unit?
Hello.
I am sorry you are having trouble using your DRV8825. The minimal connections you proposed look good. It sounds like you might have already tried to control a stepper motor. If so, can you tell me what the rated current of that stepper motor was? (Linking to a product page or datasheet for that stepper motor would work, too.) Did you install a capacitor across power and ground?
Can you post pictures that clearly show your soldering joints and connections? What are you using to turn the potentiometer? (Can you verify that the potentiometer dial is actually rotating?)
-Jon
My stepper is NEMA 17 Rated current (one-phase): 1.3A DC / Rated voltage: 2.4V - I didn’t get as far as putting a capacitor in just because I wanted to get the correct VREF voltage first. It is not needed to set vref voltage is it?
I can verify the pot is turning, I use a micro flat head electronics screwdriver. I even tested the pot with my meter…
Pot turned fully counter-clockwise reads 7.4kohm on top left pin and 18 ohm on top right pin
Pot turned fully clockwise reads 20ohm on top left pin and 7.35kohm on top right pin
A capacitor across the motor supply is not needed to set the VREF voltage, but it is important to add to a system in order to prevent destructive LC voltage spikes. It sounds like your stepper motor driver is damaged; this could have been a result of an LC voltage spike. Also, it is not clear if you ever tried to use the driver with your stepper motor attached. Stepper motor drivers can also be damaged if a stepper motor is attached to their outputs, and the current limit was not appropriately set.
If you email us with your salesorder information and refer to this forum post, we might be able to help you out with a replacement.
-Jon
