L9110S Module Overview

Motor Power & Current

The VCC connection powers the motor driver and supplies the energy used by the motors. There is no separate motor-power and logic-power input on this module.

• Keep the supply voltage within both the module rating and the motor's rated voltage.
• Check the motor stall current, not only its no-load or normal running current.
• The stated 0.8A figure should be treated as an upper driver rating rather than a preferred continuous operating point. Allow practical thermal margin.
• The small PCB and driver ICs can become hot when operating near their current limit.
• The voltage reaching the motor will be somewhat lower than VCC under load because of losses in the H-bridge.
• The onboard power LED indicates that supply voltage is present; it does not confirm that the supply voltage or motor current is safe.

Module Connections

The supplied board uses the following control labels. Some listings omit the hyphen and show AIA, AIB, BIA and BIB instead.

On the pictured board, with the screw terminals towards you and the 6-pin header along the opposite edge, the header is labelled A-IB, A-IA, VCC, GND, B-IB and B-IA. Always check the silkscreen on the actual module before wiring it.

Arduino UNO Wiring – Two DC Motors

Direction, Stop & PWM Logic

Each motor channel has two logic inputs. The A channel uses A-IA and A-IB, while the B channel works the same way using B-IA and B-IB.

For PWM speed control, keep one input LOW and apply PWM to the other. Reverse direction by moving the PWM signal to the opposite input.

Arduino Test – Two DC Motors

No additional Arduino library is required for this example. Connect the module as shown above, use an appropriate external motor supply and check the wiring before applying power.

const int A_IA = 5;
const int A_IB = 6;
const int B_IA = 9;
const int B_IB = 10;

void setMotorA(int speedValue) {
  speedValue = constrain(speedValue, -255, 255);

  // Stop both inputs before changing direction.
  digitalWrite(A_IA, LOW);
  digitalWrite(A_IB, LOW);

  if (speedValue > 0) {
    analogWrite(A_IA, speedValue);
  } else if (speedValue < 0) {
    analogWrite(A_IB, -speedValue);
  }
}

void setMotorB(int speedValue) {
  speedValue = constrain(speedValue, -255, 255);

  // Stop both inputs before changing direction.
  digitalWrite(B_IA, LOW);
  digitalWrite(B_IB, LOW);

  if (speedValue > 0) {
    analogWrite(B_IA, speedValue);
  } else if (speedValue < 0) {
    analogWrite(B_IB, -speedValue);
  }
}

void stopMotors() {
  digitalWrite(A_IA, LOW);
  digitalWrite(A_IB, LOW);
  digitalWrite(B_IA, LOW);
  digitalWrite(B_IB, LOW);
}

void setup() {
  pinMode(A_IA, OUTPUT);
  pinMode(A_IB, OUTPUT);
  pinMode(B_IA, OUTPUT);
  pinMode(B_IB, OUTPUT);

  stopMotors();
}

void loop() {
  // About 70% PWM duty cycle.
  setMotorA(180);
  setMotorB(180);
  delay(2000);

  stopMotors();
  delay(1000);

  // Reverse both motors.
  setMotorA(-180);
  setMotorB(-180);
  delay(2000);

  stopMotors();
  delay(2000);
}

Expected Result

Both motors should run for two seconds, stop for one second, then run in the opposite direction for two seconds before stopping again. The sequence then repeats.

If a motor does not start at a PWM value of 180, temporarily test with 255. Small DC motors often need a higher duty cycle to overcome starting friction than they need once already moving.

Using a 4-Wire Bipolar Stepper Motor

The two H-bridges can also drive the two windings of a small 4-wire bipolar stepper motor. Use a multimeter to identify the two separate winding pairs before connecting the motor.

A 5-wire unipolar stepper such as an unmodified 28BYJ-48 is not a direct match for this 4-wire bipolar connection.

Arduino Stepper Library

The example below uses the official Arduino Stepper library. It is normally available with the Arduino IDE. If the compiler reports that Stepper.h cannot be found, open Library Manager and install Stepper by Arduino.

Set STEPS_PER_REV to the full-step count specified for your actual motor before using the RPM value as a meaningful shaft speed.

#include <Stepper.h>

const int A_IA = 5;
const int A_IB = 6;
const int B_IA = 9;
const int B_IB = 10;

// Change this to match your motor.
const int STEPS_PER_REV = 200;

Stepper motor(
  STEPS_PER_REV,
  A_IA,
  A_IB,
  B_IA,
  B_IB
);

void releaseMotor() {
  // Remove drive from the windings between movements.
  digitalWrite(A_IA, LOW);
  digitalWrite(A_IB, LOW);
  digitalWrite(B_IA, LOW);
  digitalWrite(B_IB, LOW);
}

void setup() {
  motor.setSpeed(10);
}

void loop() {
  motor.step(STEPS_PER_REV);
  releaseMotor();
  delay(1000);

  motor.step(-STEPS_PER_REV);
  releaseMotor();
  delay(1000);
}

Expected Result

The stepper should move one configured revolution in one direction, pause, then move the same number of steps in the opposite direction. If the motor only vibrates or locks without rotating, check that each output pair is connected to one complete winding rather than mixing wires from the two windings.

Troubleshooting