I am using DRV8825s for my 2A holding torque stepper motors.
I have noticed that the current setting via Potentiometer doesn’t correspond to the measured current
through one coil (Multimeter with RMS current measurement) when the motor is turning.
I know the RMS current divided by sqrt(2) lower than the max. current.
I know that the max current is only 70% for full step mode ( I used 1/4 and 1/8 step mode)
I know it is only possible to set these drivers to 2A max current with a sufficient cooling, but the measured current doesn’t correspond to low values either.
The shunt resistor ist 0.1Ohm for both H-Bridges (both coils).
I would expect the max current to be 2A when setting the Potentiometer to 1V. However, I can only measure 1.4A (max. current) / 1.0A (RMS current).
I have tried both RMS measurement (when the motor is turning) and DC current measurement when only one coil is energized (0° electrical angle). Both values correspond to each other but don’t correspond to the adjusted voltage on the Potentiometer.