#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define I2C_ADDR    0x27
#define LCD_COLUMNS 16
#define LCD_LINES   2
LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);
Adafruit_MPU6050 mpu;

#define buzzer 12 // buzzer pin
#define led 13 //led pin

int xsample=0;
int ysample=0;
int zsample=0;
long start;
int buz=0;

#define samples 50
#define maxVal 18 // max change limit
#define minVal -18 // min change limit
#define buzTime 5000 // buzzer on time

sensors_event_t event;

void setup(void) {
  Serial.begin(115200);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.begin(16,2); //initializing lcd


  while (!mpu.begin()) {
    lcd.print("MPU6050 not connected!");
    delay(1000);
  }
  lcd.print("MPU6050 ready!");

  lcd.print("EarthQuake ");
  lcd.setCursor(0,1);
  lcd.print("Detector ");
  delay(2000);
  lcd.clear();
  lcd.print("Calibrating.....");
  lcd.setCursor(0,1);
  lcd.print("Please wait...");

  pinMode(buzzer, OUTPUT);
  pinMode(led, OUTPUT);
  buz=0;
  digitalWrite(buzzer, buz);
  digitalWrite(led, buz); 

  for(int i=0;i<samples;i++) // taking samples for calibration
  {   
    xsample+=event.acceleration.x;
    ysample+=event.acceleration.y;
    zsample+=event.acceleration.z;
  }
  
  xsample/=samples; // taking avg for x
  ysample/=samples; // taking avg for y
  zsample/=samples; // taking avg for z 

  delay(3000);
  lcd.clear();
  lcd.print("Calibrated");
  delay(1000);
  lcd.clear();
  lcd.print("Device Ready");
  delay(1000);
  lcd.clear();
  //lcd.print(" X Y Z ");

}



void loop() {
  mpu.getAccelerometerSensor()->getEvent(&event);

  Serial.print("[");
  Serial.print(millis());
  Serial.print("] X: ");
  Serial.print(event.acceleration.x);
  Serial.print(", Y: ");
  Serial.print(event.acceleration.y);
  Serial.print(", Z: ");
  Serial.print(event.acceleration.z);
  Serial.println(" m/s^2");
  delay(500);

  int value1=event.acceleration.x; // reading x out
  int value2=event.acceleration.y; //reading y out
  int value3=event.acceleration.z; //reading z out
  
  int xValue=xsample-value1; // finding change in x
  int yValue=ysample-value2; // finding change in y
  int zValue=zsample-value3; // finding change in z
 
  /* comparing change with predefined limits*/
  if(xValue < minVal || xValue > maxVal || yValue < minVal || yValue > maxVal || zValue < minVal || zValue > maxVal)
  {
    if(buz == 0)
    start=millis(); // timer start
    buz=1; // buzzer / led flag activated
  }
  
  if(buz == 1) // buzzer flag activated then alerting earthquake
  {
    lcd.setCursor(0,0);
    lcd.print("Earthquake Alert ");
    if(millis()>= start+buzTime)
    buz=0;
  }  
  else
  {
    lcd.clear();
    lcd.print("Normal Situation");
    //lcd.print(" X Y Z ");
  }

  digitalWrite(buzzer, buz); // buzzer on and off command
  digitalWrite(led, buz); // led on and off command  
}