const int LEFT_SENSOR  = 7;
const int RIGHT_SENSOR = 8;

// Пины драйвера MX1508
const int LEFT_IN1  = 5;
const int LEFT_IN2  = 6;
const int RIGHT_IN1 = 9;
const int RIGHT_IN2 = 10;

int baseSpeed = 170;

void setup() {
  pinMode(LEFT_SENSOR, INPUT);
  pinMode(RIGHT_SENSOR, INPUT);

  pinMode(LEFT_IN1, OUTPUT);
  pinMode(LEFT_IN2, OUTPUT);
  pinMode(RIGHT_IN1, OUTPUT);
  pinMode(RIGHT_IN2, OUTPUT);

  stopMotors();
}

void loop() {
  int leftValue  = digitalRead(LEFT_SENSOR);
  int rightValue = digitalRead(RIGHT_SENSOR);

  // Предположим:
  // 0 = датчик видит чёрную линию
  // 1 = датчик видит светлую поверхность

  if (leftValue == 0 && rightValue == 0) {
    moveForward();
  }
  else if (leftValue == 0 && rightValue == 1) {
    turnLeft();
  }
  else if (leftValue == 1 && rightValue == 0) {
    turnRight();
  }
  else {
    stopMotors();
  }
}

void moveForward() {
  analogWrite(LEFT_IN1, baseSpeed);
  analogWrite(LEFT_IN2, 0);
  analogWrite(RIGHT_IN1, baseSpeed);
  analogWrite(RIGHT_IN2, 0);
}

void turnLeft() {
  analogWrite(LEFT_IN1, 0);
  analogWrite(LEFT_IN2, 0);
  analogWrite(RIGHT_IN1, baseSpeed);
  analogWrite(RIGHT_IN2, 0);
}

void turnRight() {
  analogWrite(LEFT_IN1, baseSpeed);
  analogWrite(LEFT_IN2, 0);
  analogWrite(RIGHT_IN1, 0);
  analogWrite(RIGHT_IN2, 0);
}

void stopMotors() {
  analogWrite(LEFT_IN1, 0);
  analogWrite(LEFT_IN2, 0);
  analogWrite(RIGHT_IN1, 0);
  analogWrite(RIGHT_IN2, 0);
}