void motorB(int speed) if (speed > 0) digitalWrite(IN3, HIGH); digitalWrite(IN4, LOW); else if (speed < 0) digitalWrite(IN3, LOW); digitalWrite(IN4, HIGH); speed = -speed; else digitalWrite(IN3, LOW); digitalWrite(IN4, LOW);
You can drive a small (e.g., 28BYJ-48 as bipolar mod) or a unipolar stepper. hw 130 motor control shield for arduino datasheet better