// Initialize pins
int motor_direction = 8; // motor direction
int motor_PWM = 10; // motor PWM

// Set variables
 int PWM_speed = 0; // PWM speed
 int PWM_ontime = 5; //PWM steps


void setup() {
pinMode(motor_direction, OUTPUT); // Set Pinmode 
pinMode(motor_PWM, OUTPUT);
}

void loop() {
 digitalWrite(motor_PWM, HIGH);
 while(PWM_speed < 255){
 analogWrite(motor_PWM, PWM_speed);
  PWM_speed = PWM_speed + PWM_ontime;
  delay(30);
  }
 while(PWM_speed > 0){
  analogWrite(motor_PWM, PWM_speed);
  PWM_speed = PWM_speed - PWM_ontime;
  delay(30);
 }
}