#include "LiquidCrystal_I2C.h"

#define I2C_ADDR    0x27
#define LCD_COLUMNS 20
#define LCD_LINES   4

// Define pin connections
#define TRIG_PIN D9
#define ECHO_PIN D8
#define BUZZER_PIN D10

LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

void setup() {
  Serial.begin(115200);
  Serial.println("Hello, STM32!");

  lcd.init();
  lcd.backlight();

  lcd.setCursor(4, 0);
  lcd.print("Hello, STM32");
  lcd.setCursor(5, 2);
  lcd.print("Welcome to");
  lcd.setCursor(7, 3);
  lcd.print("Wokwi!");

  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  
  // Set up the buzzer pin
  pinMode(BUZZER_PIN, OUTPUT);

}

void loop() {
  long duration, distance;

  // Clear the trigPin
//  digitalWrite(TRIG_PIN, LOW);
  //delayMicroseconds(5);

  // Sets the trigPin on HIGH state for 10 microseconds
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(ECHO_PIN, HIGH);

  // Calculating the distance
  distance = duration * 0.034 / 2;

  // Prints the distance on the Serial Monitor for debugging
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Set the cursor to column 0, line 1
  lcd.setCursor(10, 0);
  lcd.print("    ");
  lcd.setCursor(10, 0);
  lcd.print(distance);
  lcd.print(" cm");

  // Check if distance is within threshold
  if (distance < 20) {
    digitalWrite(BUZZER_PIN, HIGH);
  } else {
    digitalWrite(BUZZER_PIN, LOW);
  }

  delay(500);
}