const int IN1 = 8;
const int IN2 = 9;
const int ENA = 10;

void setup() {
    pinMode(IN1, OUTPUT);
    pinMode(IN2, OUTPUT);
    pinMode(ENA, OUTPUT);

    analogWrite(ENA, 255);
}

void loop() {
    digitalWrite(IN1, HIGH);
    digitalWrite(IN2, LOW);
    delay(3000);

    digitalWrite(IN1, LOW);
    digitalWrite(IN2, LOW);
    delay(1000);

    digitalWrite(IN1, LOW);
    digitalWrite(IN2, HIGH);
    delay(3000);

    digitalWrite(IN1, LOW);
    digitalWrite(IN2, LOW);
    delay(1000);
}