What are the different stepper motor driving modes?

Hello everyone. Full stepping, half stepping and microstepping determine the sequence and magnitude of currents applied to motor phases. As explained in the stepper operating principle, the rotor follows the magnetic field produced by those currents. The selected mode affects command resolution, motion smoothness and vibration behaviour.

One-phase-on and two-phase-on operation are different implementations of full stepping; listing them as completely separate resolution classes can be misleading. These examples use a two-phase, 1.8° hybrid motor. The stepper motor knowledge hub covers other motor and driver arrangements.

Full stepping: One phase or two phases energised

One-phase-on operation — wave drive: Only one phase carries current at a time. An illustrative sequence is A+, B+, A−, B−. In two-phase-on full stepping, A and B carry current together, with their directions changed in sequence. A+/B+, A−/B+, A−/B−, A+/B− is one example. The signs indicate phase-current direction, not control-input names.

Both arrangements retain this motor's basic 1.8° step interval and 200 full steps per revolution, although their initial equilibrium positions can differ. At the same phase-current magnitude, energising two phases can produce a stronger resultant magnetic field, but also increases copper losses. A current-regulated driver may scale the current levels. Full stepping does not universally provide the highest torque under every operating condition.

Half stepping: Adding intermediate positions

Half stepping inserts a position between each pair of full-step positions. The example gives a 0.9° command interval and 400 pulses/rev. A traditional sequence alternates one-phase-on and two-phase-on states. Keeping phase-current magnitudes unchanged varies the field magnitude; current-compensated half stepping adjusts the levels to reduce that variation.

There is therefore no single torque-reduction percentage applicable to every half-step driver. Assess torque together with phase current, driver method and speed. A smaller step interval does not guarantee an equally small physical movement under load.

Microstepping: Changing phase currents progressively

Microstepping changes the ratio of phase currents in small increments. An ideal two-phase model uses IA = Imax × cos φ and IB = Imax × sin φ. Here, φ is the electrical field angle, not the mechanical shaft angle. Dividing a full step into sixteenths gives a 0.1125° command interval and requires 3200 pulses per revolution.

With a STEP/DIR interface, each pulse supplies a command increment. The driver's PWM/chopper switching regulates phase current. STEP frequency and PWM frequency are different quantities. Motor windings are not connected directly to a controller's STEP output.

Two misconceptions about microstep accuracy and torque

Increasing command resolution does not increase position accuracy in the same proportion. Motor tolerances, friction, load and current-regulation quality affect the result. Small commands may accumulate before the rotor moves. 1/16 microstepping does not mean total running torque falls to one sixteenth. Distinguish the incremental effect of one microstep from overall rotational torque.

Microstepping can reduce vibration and noise, but cannot eliminate resonance or lost steps under every condition. An encoder-equipped stepper with a suitable driver can provide position feedback. Closed-loop control and microstepping are compatible features, not competing alternatives.

The same speed needs a different pulse frequency

For a 1.8° motor commanded to 300 rpm, without electronic gearing or interpolation, full stepping needs 1000 Hz, half stepping 2000 Hz, and 1/16 microstepping 16,000 Hz. In speed and position control, account for both pulses/rev and the controller's frequency limit. Keeping the same 1000 Hz input at 1/16 instead commands 18.75 rpm.

Current decay mode is not a step division

Some drivers offer slow decay, fast decay and mixed decay. These determine power-stage behaviour while winding current is reduced; they do not select resolution in the way full stepping or 1/16 does. Decay selection can affect current ripple, noise and current tracking. No single decay setting is best for every motor and speed.

Assess supply voltage, winding inductance and phase current together. The power supply must support the load, and thermal management must respect motor and driver limits. More microsteps do not automatically mean lower temperatures.

How should a drive mode be selected?

Start with the application requirements: low-speed smoothness, mechanical vibration and available pulse frequency matter. When choosing a motor and driver, look beyond the highest advertised microstep number. Without mechanical inspection, software settings may fail to solve backlash or coupling problems.

Technical references: Analog Devices — microstepping and accuracy; Texas Instruments — DRV8825 phase-current table and decay modes.