VL53L0X Laser Distance Meter

// VL53L0X Laser Distance Meter - a contactless tape measure + parking alarm.
// Click the VL53L0X on the bench and drag its distance slider while the sketch
// runs - the OLED shows the range in cm with a proximity bar, and the red LED
// lights with TOO CLOSE when something comes within 10 cm.

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <VL53L0X.h>

#define ALERT_PIN 4
#define NEAR_MM 300    // under 30 cm = NEAR
#define CLOSE_MM 100   // under 10 cm = TOO CLOSE

Adafruit_SSD1306 display(128, 64, &Wire, -1);
VL53L0X sensor;

void setup() {
  Serial.begin(115200);
  pinMode(ALERT_PIN, OUTPUT);
  Wire.begin();
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.display();
  sensor.setTimeout(500);
  sensor.init();
  sensor.startContinuous();
  Serial.println("Distance meter ready - drag the VL53L0X slider");
}

void loop() {
  uint16_t mm = sensor.readRangeContinuousMillimeters();
  float cm = mm / 10.0;
  bool close = mm < CLOSE_MM;
  bool near = mm < NEAR_MM;
  digitalWrite(ALERT_PIN, close ? HIGH : LOW);

  const char* zone = close ? "TOO CLOSE" : near ? "NEAR" : "CLEAR";

  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.print("LASER DISTANCE");
  display.setTextSize(3);
  display.setCursor(0, 16);
  display.print((int)(cm + 0.5));
  display.setTextSize(2);
  display.print(" cm");
  display.setTextSize(1);
  display.setCursor(0, 44);
  display.print(zone);
  // proximity bar: full at 0 mm, empty at 2000 mm
  long barW = 128 - (mm * 128L / 2000);
  if (barW < 0) barW = 0;
  if (barW > 128) barW = 128;
  display.fillRect(0, 56, (int)barW, 8, SSD1306_WHITE);
  display.display();

  Serial.print("Range: ");
  Serial.print(mm);
  Serial.print(" mm  (");
  Serial.print(cm, 1);
  Serial.print(" cm) ");
  Serial.println(zone);
  delay(200);
}