Linear actuator out and back on an Arduino Uno

// A 12 V linear actuator on an L298N, all the way out and back.
//
//   L298N IN1 -> pin 8    IN2 -> pin 9    (ENA jumper on)
//   L298N OUT1 -> actuator M+    OUT2 -> actuator M-
//   L298N 12V -> 12 V,  GND -> GND (shared with the Uno)
//
// The 100 mm stroke takes about 8 s at 12.7 mm/s, and the L298N keeps some of
// the 12 V, so it is slower here. The sketch drives each way for 12 s anyway:
// the actuator's own limit switch stops it at the end, and the other way
// still runs at once. No position sensor needed.

const int IN1 = 8;
const int IN2 = 9;

void drive(int a, int b, const char *what) {
  digitalWrite(IN1, a);
  digitalWrite(IN2, b);
  Serial.println(what);
}

void setup() {
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  Serial.begin(9600);
  Serial.println("Mokxi Uno: linear actuator, out and in");
}

void loop() {
  drive(HIGH, LOW, "out");
  delay(12000);
  drive(LOW, LOW, "stop");
  delay(1000);
  drive(LOW, HIGH, "in");
  delay(12000);
  drive(LOW, LOW, "stop");
  delay(1000);
}