A4988 driver microstepping question

Noob warning… :smiley:

I’ve put together a circuit using an A4988 driver to drive a 2.8V 1.68A/phase stepper. I’m using an Arduino to run it and a 12V, 6A power supply. I’m trying to use 1/16 microstepping and run the motor at 3 rpm. I want to use microstepping to smooth out the movement. I set the current limit by measuring VREF to as close I can to 0.672V. (0.672 * 2.5 = 1.68)

The problem I’m running into is that microstepping isn’t moving the motor. I can hear the motor pulsing with each microstep, but it only moves when it hits the full step. I’ve read the data sheet for the driver and I realize torque drops significantly at 1/16 microstepping. Would it possibly fix my problem by changing to 1/8 or 1/4 microstepping? Would a different current limit setting help? Any other thoughts of what I could try?

Any suggestions would be appreciated.



I am sorry you are having problems with your stepper motor and driver. The A4988 stepper motor driver might have some problems driving that motor. Although the datasheet for the A4988 lists 2A as the absolute maximum output current it can handle with sufficient cooling, it typically only delivers approximately 1A per phase (the Black Edition delivers approximately 1.2A per phase), which is lower than the rated current of your motor. You might try lowering the current limit and changing microstepping modes to see if that helps. You also might consider adding additional cooling to your driver, but I do not have any specific recommendations for that. Alternatively, you could try upgrading to the DRV8825 stepper motor driver carrier, though it can only deliver up to 1.5A with out any additional cooling.

- Jeremy

Thanks. I’ll try that.