#define TRIG_PIN PA0
#define ECHO_PIN PA1

void setup() {
  Serial.begin(115200);

  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  digitalWrite(TRIG_PIN, LOW);
}

void loop() {
  long duration;
  float distance;

  // Send 10 microsecond trigger pulse
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);

  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Read echo pulse
  duration = pulseIn(ECHO_PIN, HIGH);

  // Calculate distance in cm
  distance = duration / 58.0;

  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  delay(500);
}