#include "HX711.h"
#include <ArduinoBLE.h>#include <Wire.h> 
#include <LiquidCrystal_I2C.h>
#include <Wire.h> 


LiquidCrystal_I2C lcd(0x27,20,4);  // set the LCD address to 0x27 for a 16 chars and 2 line display
HX711 scale;

BLEService ledService("19B10000-E8F2-537E-4F6C-D104768A1214"); // BLE LED Service

// BLE LED Switch Characteristic - custom 128-bit UUID, read and writable by central
BLEByteCharacteristic switchCharacteristic("19B10001-E8F2-537E-4F6C-D104768A1214", BLERead | BLEWrite);

BLEUnsignedCharCharacteristic WeightLevelChar("2A19",  // standard 16-bit characteristic UUID
    BLERead | BLENotify); // remote clients will be able to get notifications if this characteristic changes

int oldBatteryLevel = 0;  // last battery level reading from analog input
long previousMillis = 0;  // last time the battery level was checked, in ms
const int ledPin = LED_BUILTIN; // pin to use for the LED
 double val;

void setup() {
  lcd.begin();
  lcd.backlight();
  lcd.clear();
  lcd.print("Power on! :)");
  lcd.setCursor (0,1);
  lcd.print("calibrating...  ");
  
  Serial.begin(9600);
  scale.begin(A1, A0);    //Initialized scale on these pins
  while (!Serial);

  scale.set_scale(432.f);                      // this value is obtained by calibrating the scale with known weights; see the README for details
  scale.tare();               // reset the scale to 0
  

  // set LED pin to output mode
  pinMode(ledPin, OUTPUT);

  // begin initialization
  if (!BLE.begin()) {
    Serial.println("starting BLE failed!");

    while (1);
  }

  // set advertised local name and service UUID:
  BLE.setLocalName("COFFEE");
  BLE.setAdvertisedService(ledService);

  // add the characteristic to the service
  ledService.addCharacteristic(switchCharacteristic);
  ledService.addCharacteristic(WeightLevelChar); // add the battery level characteristic


  // add service
  BLE.addService(ledService);

  // set the initial value for the characeristic:
  switchCharacteristic.writeValue(0);

  // start advertising
  BLE.advertise();

  Serial.println("BLE LED Peripheral");
}



void loop() 
{

  // listen for BLE peripherals to connect:
  BLEDevice central = BLE.central();

  // if a central is connected to peripheral:
  if (central) {
    Serial.print("Connected to central: ");
    // print the central's MAC address:
    Serial.println(central.address());

    // while the central is still connected to peripheral:
    while (central.connected()) 
    {
      
      // Battery Monitor 
      //  scale.read();
        long currentMillis = millis();
      // if 200ms have passed, check the battery level:
      if (currentMillis - previousMillis >= 200) {
         previousMillis = currentMillis;
       // scale.read();
       // updateBatteryLevel();
      //  scale.get_offset();
      //  scale.get_scale();
        outputScale();
      }
      // if the remote device wrote to the characteristic,
      // use the value to control the LED:
      if (switchCharacteristic.written()) {
        if (switchCharacteristic.value()) {   // any value other than 0
          Serial.println("LED on");
          digitalWrite(ledPin, HIGH);         // will turn the LED on
        } else {                              // a 0 value
          Serial.println(F("LED off"));
          digitalWrite(ledPin, LOW);          // will turn the LED off
        }
      }
      
    }

    // when the central disconnects, print it out:
    Serial.print(F("Disconnected from central: "));
    Serial.println(central.address());
  }else{
      lcd.clear();
  lcd.print("Awaiting BLE...  ");
  lcd.setCursor (0,1);
  lcd.print("Connect smartphone");
  }
  
  
}
void updateBatteryLevel() 
{
  /* Read the current voltage level on the A0 analog input pin.
     This is used here to simulate the charge level of a battery.
  */
  int battery = analogRead(A3);
  int batteryLevel = map(battery, 0, 1023, 0, 100);

  if (batteryLevel != oldBatteryLevel) {      // if the battery level has changed
   // Serial.print("Battery Level % is now: "); // print it
   
    Serial.println(batteryLevel);
    WeightLevelChar.writeValue(batteryLevel);  // and update the battery level characteristic
    oldBatteryLevel = batteryLevel;           // save the level for next comparison
  }
}

void outputScale()
{
       int t, i, n, T;
       n=7;
       i=0;
  double val, sum, sumsq, mean;
  float stddev;

  float oldVal;

     while (i<n) 
  {
        val = ((scale.read() - scale.get_offset()) / scale.get_scale());
     if (val != oldVal)
     {      // if the battery level has changed
   // Serial.print("Battery Level % is now: "); // print it

   
   // Serial.println(batteryLevel);
    WeightLevelChar.writeValue(val);  // and update the battery level characteristic
    oldVal = val;           // save the level for next comparison
     }
    sum += val;
    i++;
  }
  mean = sum / n;
  if(i>=n){
    i=0;
  }
     
     Serial.print(val);
     Serial.print("\n"); 

  lcd.clear();
  lcd.print("weight:  ");
  lcd.print(val);  
  lcd.setCursor (0,1);
  lcd.print("mean:    ");
  lcd.print(mean);
/*
  
  n = 20;
  t = millis();
  i = sum = sumsq = 0;
  while (i<n) {
    val = ((scale.read() - scale.get_offset()) / scale.get_scale());
    sum += val;
    sumsq += val * val;
    i++;
  }
  t = millis() - t;
  mean = sum / n;
  stddev = sqrt(sumsq / n - mean * mean);
  val = scale.read();
 Serial.print(mean, 3); Serial.print("\n"); 
 */
}