#include <LiquidCrystal.h> /* LCD Library */
#include <avr/wdt.h>       /* watch dog timer functions */
//button press checker
#define PD2ON 0x04  /* 0000 0100 WATCH DOG BUTTON */
#define PD3ON 0x08  /* 0000 1000 STOP BUTTON */
#define PD4ON 0x10  /* 0001 0000 COUNT_DOWN BUTTON */
#define PD5ON 0x20  /* 0010 0000 COUNT_UP  BUTTON */
#define wdt_reset() __asm__ __volatile__ ("wdr")
const int rs = 12, en = 11, d4 = 10, d5 = 8, d6 = 7, d7 = 6;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
// list of prohibited libraries
bool upCheck = false;       /* check if button 1 is clicked */
bool downCheck = false;     /* check if button 2 is clicked */
bool stopCheck = false;     /* check if button 3 is clicked */
bool lcdState = true;       /* check if the lcd is available */
bool wdState = false;       /* check if button 4 is clicked */
float timer = 0.0;          /* time value */
float mills = 1562.5;       /* initial millisecond value */
unsigned int wdtValue = 0; /* wdt value */
int stateValue;
String state[] = {"STOP      ", "COUNT_DOWN", "COUNT_UP"};
void setup() {
  // Set up Timer1
  Serial.begin(9600);
  lcd.begin(16, 2);
  lcd.print("STOP");
  lcd.setCursor(0, 1);
  lcd.print("00.0s");
  lcd.setCursor(6, 1);
  lcd.print("wait:000ms");
  DDRD &= ~0xC3;
  noInterrupts();  // Disable all interrupts
  TCCR1A = 0;  // Reset Timer/Counter Control Register (TCCR1A) register
  TCCR1B = 0;  // Reset Timer/Counter Control Register (TCCR1B) register
  // Set the prescaler to 1024
  TCCR1B |= 0x05;
  // Set the compare match value for 1s
  OCR1A = mills;  //（15625 ≒ 1s / (1 / (16MHz / 1024)))
  // Set the Clear Timer on Compare(CTC) mode
  TCCR1B |= (1 << WGM12);
  // Enable Timer1 compare match A interrupt
  TIMSK1 |= (1 << OCIE1A);
  interrupts();    // Enable all interrupts
  wdt_disable();
  delay(500);
  wdt_enable(WDTO_250MS);
}
void loop() {
  // put your main code here, to run repeatedly:
  lcd.setCursor(0, 0);
  lcd.print(state[stateValue]);
  lcd.setCursor(0, 1);
  if (timer <= 9.99) {
    lcd.print(0);
  }
  lcd.print(timer, 1);
  lcd.print("s wait:");
  lcd.setCursor(11, 1);
  if (wdtValue <= 1 ) {
    lcd.print(0);
  }
  delay(60 * wdtValue);
  if (wdtValue < 250) {
    lcd.print(60 * wdtValue);
  }
  wdt_reset();
}
ISR(WDT_vect) {
  OCR1A = mills;
  wdtValue = 0;
  timer = 0.0;
  stateValue = 0;
}
// Timer1 compare match A interrupt service routine
ISR(TIMER1_COMPA_vect) {
  int wdtState;
  static int lastWdtState = PIND & 0x04;
  //if button press
  if (PIND & PD5ON && lcdState == true) {         /* count up button press */
    upCheck = true;
    downCheck = false;
    stopCheck = false;
  } else if (PIND & PD4ON && lcdState == true) {  /* count down button press */
    downCheck = true;
    upCheck = false;
    stopCheck = false;
  } else if (PIND & PD3ON && lcdState == false) { /* stop button press */
    lcdState = true;
    stopCheck = true;
  } else if (PIND & PD3ON && lcdState == true) {  /* stop button press again */
    timer = 0.0;
  } else if (PIND & 0x04) {                      /* watch dog button press again */
    wdtState = (PIND & 0x04);
    if (lastWdtState == wdtState) {
    //nothing will happen
    } else {
      if (wdtState < 250) {
        wdtValue++;
      }
      lastWdtState = wdtState;
    }
  } else {
    lastWdtState = wdtState;
  }
  //button funtion
  if (upCheck == true && stopCheck == false) {           /* COUNT_UP */
    timer += 0.1;                   /* timer increase */
    lcdState = false;
    if (timer >= 20.0) {            /* if timer goes to 20 */
      timer = 20.0;
      stateValue = 0;
      lcdState = true;
    } else {                        /* else COUNT_UP */
      stateValue = 2;
    }
  } else if (downCheck == true && stopCheck == false) { /* COUNT_DOWN */
    timer -= 0.1;                   /* timer decrease */
    lcdState = false;
    if (timer <= 0.0) {             /* if timer goes to 0 */
      timer = 0.0;
      stateValue = 0;
      lcdState = true;
    } else {                        /* else COUNT_DOWN */
      stateValue = 1;
    }
  } else if (stopCheck == true) {                       /* STOP */
    stateValue = 0;
  }
}