#include <LiquidCrystal.h>
#include <JC_Button.h>
 
const float Low_BAT_level = 3.2;
 
//Current steps with a 3R load (R7)
const int Current[] = {0, 37, 70, 103, 136, 169, 202, 235, 268, 301, 334, 367, 400, 440, 470, 500, 540};
 
const byte RS = 2, EN = 3, D4 = 4, D5 = 5, D6 = 6, D7 = 7;
const byte PWM_Pin = 10;
const byte Speaker = 12;
const int BAT_Pin = A0;
int PWM_Value = 0;
unsigned long Capacity = 0;
int ADC_Value = 0;
float BAT_Voltage = 0;
byte Hour = 0, Minute = 0, Second = 0;
bool calc = false, Done = false;
 
LiquidCrystal lcd(RS, EN, D4, D5, D6, D7);
 
Button UP_Button(16, 25, false, true);
Button Down_Button(15, 25, false, true);
 
void setup() {
 
  pinMode(PWM_Pin, OUTPUT);
  pinMode(Speaker, OUTPUT);
 
  analogWrite(PWM_Pin, PWM_Value);
 
  UP_Button.begin();
  Down_Button.begin();
 
  lcd.setCursor(0, 0);
  lcd.begin(16, 2);
  lcd.print("Battery Capacity");
  lcd.setCursor(0, 1);
  lcd.print("Measurement v1.0");
  delay(3000);
  lcd.clear();
  lcd.print("Load Adj:UP/Down");
  lcd.setCursor(0, 1);
  lcd.print("0");
 
}
 
void loop() {
 
  UP_Button.read();
  Down_Button.read();
 
  if (UP_Button.wasReleased() && PWM_Value < 80 && calc == false)
  {
    PWM_Value = PWM_Value + 5;
    analogWrite(PWM_Pin, PWM_Value);
    lcd.setCursor(0, 1);
    lcd.print("     ");
    lcd.setCursor(0, 1);
    lcd.print(String(Current[PWM_Value / 5]) + "mA");
  }
 
  if (Down_Button.wasReleased() && PWM_Value > 1 && calc == false)
  {
    PWM_Value = PWM_Value - 5;
    analogWrite(PWM_Pin, PWM_Value);
    lcd.setCursor(0, 1);
    lcd.print("     ");
    lcd.setCursor(0, 1);
    lcd.print(String(Current[PWM_Value / 5]) + "mA");
  }
 
  if (UP_Button.pressedFor(1000) && calc == false)
  {
    digitalWrite(Speaker, HIGH);
    delay(100);
    digitalWrite(Speaker, LOW);
    lcd.clear();
    timerInterrupt();
  }
 
}
 
void timerInterrupt() {
  calc = true;
  while (Done == false) {
    Second ++;
    if (Second == 60) {
      Second = 0;
      Minute ++;
      lcd.clear();
    }
    if (Minute == 60) {
      Minute = 0;
      Hour ++;
    }
    lcd.setCursor(0, 0);
    lcd.print(String(Hour) + ":" + String(Minute) + ":" + String(Second));
    lcd.setCursor(9, 0);
    ADC_Value = analogRead(BAT_Pin);
    BAT_Voltage = ADC_Value * (5.0 / 1024);
    lcd.print("V:" + String(BAT_Voltage));
    lcd.setCursor(0, 1);
    lcd.print("BAT-C: Wait!...");
 
    if (BAT_Voltage < Low_BAT_level)
    {
      lcd.setCursor(0, 1);
      lcd.print("                ");
      lcd.setCursor(0, 1);
      Capacity =  (Hour * 3600) + (Minute * 60) + Second;
      Capacity = (Capacity * Current[PWM_Value / 5]) / 3600;
      lcd.print("BAT-C:" + String(Capacity) + "mAh");
      Done = true;
      PWM_Value = 0;
      analogWrite(PWM_Pin, PWM_Value);
      digitalWrite(Speaker, HIGH);
      delay(100);
      digitalWrite(Speaker, LOW);
      delay(100);
      digitalWrite(Speaker, HIGH);
      delay(100);
      digitalWrite(Speaker, LOW);
    }
 
    delay(1000);
  }
}