Microstepping; Drv8825 - Waveshare HAT User Manual

Stepper Motor HAT User Manual
28BYJ-48 is four phase and eight steps, Speed Variation Ratio is 1/64 and its step
angle is 5.625/64 degree.

MICROSTEPPING

We have said that motor rotate because of flowing current.
According to its working principle, we can control currents in coils to make them
rise or fall regularly. It generates several stable intermediate-current statuses, related
vector directions of resultant magnetic fields also have several intermediate statuses.
To change the vector direction, motor can rotate in smaller angle and rotate more
smoothly.
Microstepping is to divide each full step into smaller steps to help smooth out the
motor's rotation, especially at slow speeds. For example, if microstepping the motor
we described above to 1/2, status 1 should be done with two steps.

DRV8825

DRV88250 control stepper motor rotating according to pulses given by MCU.
How many pulses do motors require to rotate a circle without microstepping?
42 motor: 360/1.8 = 200
28BYJ-48 motor: 360 / 5.625 * 64 = 4096
As we test, with 200 pulses, 42 motor can rotate a circle. However, with 4096 pulses,
28BYJ-48 rotate two circles. That is because 28BYJ-48 is four-phase motor require
2048 pulses for a circle actually.
12 / 24