Stepper motor: move in exact steps
How a stepper moves in exact steps (200 steps = 1 turn = 1.8° each) and how a driver board (A4988 / ULN2003) moves it from code.
You asked, @james_ece_369 — how does a stepper motor move in exact steps? ⚙️
1️⃣ INSIDE: coils switch on one after another. Each live coil pulls the magnetic rotor to it — one small step at a time. (Real steppers have a toothed rotor so the steps are tiny.)
2️⃣ HOW SMALL: most steppers take 200 steps for one full turn. 360° ÷ 200 = 1.8° per step. (The cheap 28BYJ-48 has a gearbox inside: 2048 steps per turn.)
3️⃣ THE DRIVER BOARD (A4988 / DRV8825): your Arduino sends one pulse on the STEP pin = the motor moves one step. The DIR pin sets the direction. Count the pulses and you know the exact angle — no sensor needed. That's why 3D printers and CNC machines use them.
Pulses become exact angles!
Read the voiceover (transcript)
- How does a motor move in exact steps?
- Inside, coils switch on one after another. Each one pulls the rotor one small step.
- Most steppers take two hundred steps per turn. That's one point eight degrees each!
- A driver board does the work: one pulse, one step. Another pin sets the direction.
- Pulses become exact angles!
- Next: brushless motors! Follow for Part six!
Related lessons
Get new lessons + early access to the full course
One email when new lessons drop. No spam, unsubscribe any time.
✓ You're on the list! We'll email you when new lessons drop.
By joining you agree to the privacy policy.