How to control DC motor with Arduino?

Here are two reliable ways to control a brushed DC motor with Arduino—one-direction speed control (simplest) and full direction + speed with an H-bridge.

Option A — One direction (speed only) with a logic-level N-MOSFET

Use when: you just need on/off + speed control.

Parts

• 
  Arduino (Uno/Nano/etc.)


• Logic-level N-MOSFET (e.g., IRLZ44N, IRLZ34N, AOZ1282 equivalent; not IRFZ44N)


• Flyback diode (e.g., 1N5819/SS14 or 1N5408)


• 100 Ω gate resistor, 10 kΩ gate-to-GND resistor


• 
  Motor + external motor supply (e.g., 6–12 V)


• 
  Wires; optional 100 µF bulk capacitor across motor supply

Wiring

Motor +  ─────────── +VMOTOR (battery/PSU)

Motor −  ──•── D (MOSFET)

           |

          S (MOSFET) ─── GND (shared with Arduino)

          G (MOSFET) ── 100Ω ── D9 (PWM)

                     └─ 10kΩ ── GND  (pull-down)

Flyback diode: anode to MOSFET D / motor−, cathode to +VMOTOR

Arduino GND ──────────────────── common with VMOTOR GND

Code (speed with PWM on pin 9)

const int PWM_PIN = 9;   // any PWM-capable pin (Uno: 3,5,6,9,10,11)

void setup() {

  pinMode(PWM_PIN, OUTPUT);

}

void loop() {

  // ramp up

  for (int s = 0; s <= 255; s++) { analogWrite(PWM_PIN, s); delay(10); }

  delay(1000);

  // ramp down

  for (int s = 255; s >= 0; s--) { analogWrite(PWM_PIN, s); delay(10); }

  delay(1000);

}

Notes

• Choose a MOSFET with low Rds(on) at Vgs = 4–5 V and current rating ≥ motor stall current.


• Keep Arduino 5 V separate from motor supply; only GND is common.


• Put a 0.1 µF ceramic across motor terminals (and 100 µF across supply) to tame noise.

Option B — Direction + speed with a dual H-bridge (e.g., TB6612FNG or DRV8833)

Use when: you need forward/reverse, brake, and efficient drive (better than L298N).

Parts

• Arduino


• TB6612FNG (pins: AIN1/AIN2/PWMA/STBY + BIN1/BIN2/PWMB if using 2nd channel)


• Motor + external supply (e.g., 6–12 V)


• Wires; decoupling caps

Wiring (one motor on channel A)

VM  (driver) ─── +VMOTOR

GND (driver) ─── GND (shared with Arduino & motor supply)

VCC (driver) ─── 5V from Arduino

AIN1 ─────────── D7

AIN2 ─────────── D8

PWMA ─────────── D9 (PWM)

STBY ─────────── D6 (tie HIGH to enable)

Motor A+ ─────── Motor +

Motor A− ─────── Motor −

Code (forward/reverse/brake + PWM speed)

const int AIN1 = 7, AIN2 = 8, PWMA = 9, STBY = 6;



void setup() {

  pinMode(AIN1, OUTPUT);

  pinMode(AIN2, OUTPUT);

  pinMode(PWMA, OUTPUT);

  pinMode(STBY, OUTPUT);

  digitalWrite(STBY, HIGH); // exit standby

}



void drive(int speed) { // speed: -255..255 (sign = direction)

  if (speed > 0) { digitalWrite(AIN1, HIGH); digitalWrite(AIN2, LOW); }

  else if (speed < 0) { digitalWrite(AIN1, LOW); digitalWrite(AIN2, HIGH); speed = -speed; }

  else { // brake

    digitalWrite(AIN1, HIGH); digitalWrite(AIN2, HIGH);

  }

  analogWrite(PWMA, constrain(speed, 0, 255));

}



void loop() {

  drive(180); delay(2000);   // forward

  drive(0);   delay(500);    // brake

  drive(-180);delay(2000);   // reverse

  drive(0);   delay(1000);   // brake

}

Why TB6612/DRV8833 over L298N?

Much lower losses (MOSFET vs bipolar), runs cooler, works well at 3.3–5 V logic, handles fast PWM.

Sizing & safety checklist

• Supply: motor current at load and at stall; PSU must handle stall or use current limiting/slow-start.


• Grounds: Arduino GND ↔ motor driver GND must be common.


• Protection: always include a flyback path (diode or the H-bridge’s body diodes). Add a polyfuse if you expect stalls.


• Noise/EMI: twist motor wires, add caps (0.1 µF at motor, 100 µF near driver), keep high-current loops short.


• PWM frequency: Arduino Uno PWM is ~490 Hz (pins 3,9,10,11 ~490; 5,6 ~980 Hz). For audible whine reduction, use pins 5/6 or change timer prescalers/libraries.

Picking a driver (quick guide)

• Small toy motors (<1 A): L9110S, DRV8833.


• 1–2 A range: TB6612FNG, DRV8833/DRV8838.


• >3 A or big motors: DRV8871/8876 single-channel, or a MOSFET H-bridge module; consider heat sinking.