Controller DC motor with L9110 Motor Control board

The DC motor comes with my starter kit is integrated with the LC9110 motor control board. In this exercise, I am going to make the motor moves clockwise then anti-clockwise at the speed read from the serial input.

The controller has four pins:
VCC - connected to 5v
GND - connected to ground
IA - connected to pin 9 to control speed in clockwise direction
IB - connected to pin 8 to control speed in anti-clockwise direction

/*


 L9110 motor driver controlling a small DC motor
 */

const int IA = 9;  //  pin 9 connected to pin IA
const int IB = 8;  //  pin 8 connected to pin IB


byte speed = 255;  // change this (0-255) to control the speed of the motor

void setup() {
  pinMode(IA, OUTPUT); // set pins to output
  pinMode(IB, OUTPUT);
  Serial.begin(9600);
  while (!Serial);
  Serial.println("Speed 0 to 255");
}

void loop() {
 
  if (Serial.available()) {
     speed = Serial.parseInt();
      Serial.print("Set speed to ");
      Serial.println(speed);
  }
  forward();
  delay(1000);
  backward();
  delay(1000);
}

void backward()
{
  analogWrite(IA, 0);
  analogWrite(IB, speed);
}

void forward()
{
  analogWrite(IA, speed);
  analogWrite(IB, 0);

}