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

#define Screen_Width 128
#define Screen_height 64
#define trig_pin 13
#define echo_pin 14
#define speed_sound 0.0343

unsigned long duration;
float distance;

Adafruit_SSD1306 display(Screen_Width,Screen_height, &Wire ,-1);
void setup()
{
  Wire.begin(21,22);
  Serial.begin(115200);
  pinMode(trig_pin, OUTPUT);
  pinMode(echo_pin, INPUT);

  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println("OLED failed");
    while (true);
  }

  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0,0);
  display.print("OLED WORKING");
  display.display();
}

void loop()
{
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);

  //HcSr04 block
   digitalWrite(trig_pin, LOW);
   delayMicroseconds(2);

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

   digitalWrite(trig_pin, LOW);

   duration = pulseIn(echo_pin,HIGH,30000);

   distance = (speed_sound*duration)/2;

   if (duration == 0) {

    display.setCursor(20, 25);
    display.print("Out of Range");
   }
   else{

   //kalakari barGraph ki
   int barwidth = map(distance , 0 , 400, 0, 120);
   barwidth = constrain(barwidth,0,120);

   //title
   display.setCursor(4,5);
   display.print("ULTRASONIC SENSORS");

   //features
   display.setCursor(4,18);
   display.print("Distance:-  ");
   display.print(distance , 1);

   //Bar-Graph display
   display.drawRect(4, 35, 120, 12, WHITE);
   display.fillRect(4, 35, barwidth, 12, WHITE);
   }
   display.display();
   delay(500);
}