ActuatorsQUICK REFERENCE
Stepper Motor
Identify coil pairs and wire a bipolar stepper to a STEP/DIR driver.
01Coils & wiring
- Identify
- With power disconnected, measure resistance to find the two coil pairs of a 4-wire bipolar motor.
- Connect
- One pair to A1/A2, the other to B1/B2. Driver labels may be 1A/1B and 2A/2B.
- Control
- MCU STEP → STEP; DIR → DIR; common GND. Configure enable/sleep/reset as required.
02STEP / DIR
- Motion
- Each STEP pulse advances one configured microstep. DIR selects direction.
- Rate
- Step frequency sets speed; ramp frequency to avoid missed steps.
- Position
- steps = revolutions × full_steps_per_rev × microstep_factor. A 1.8° motor has 200 full steps/rev.
03Driver setup
- Current limit
- Set using the exact driver and sense-resistor formula before running the motor.
- Supply
- Use rated VMOT supply and local bulk capacitor; A4988 carriers can suffer damaging LC spikes.
- Variants
- 5-wire 28BYJ-48 + ULN2003 uses a coil sequence, not STEP/DIR directly.