#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 
#define SCREEN_HEIGHT 64 
#define ECHO_PIN 32 
#define TRIG_PIN 33 
#define SDA_PIN 21
#define SCL_PIN 19

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT);

void setup() {

  Serial.begin(115200);

  Wire.begin(SDA_PIN, SCL_PIN);

  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { 
    Serial.println("SSD1306 allocation failed");
    for(;;);
  }
  
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);

}
void loop() {
  long duration, distance;

  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);

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

  digitalWrite(TRIG_PIN, LOW);

  duration = pulseIn(ECHO_PIN, HIGH);
  distance = duration * 0.034 / 2;

  display.clearDisplay();
  display.setCursor(0, 0);
  display.setTextSize(2);
  display.setTextColor(WHITE);

  if (distance < 200) {
    display.print("Occupied");
  } else {
    display.print("Free");
  }

  display.display();
  delay(1000);
}