#include "Wire.h"
#define DS3231_I2C_ADDRESS 0x68 //adresa ds2328

#include <LiquidCrystal_I2C.h>
 
// Nastav I2C addresu, piny PCF8574 a podsviceni
//                    addr, en,rw,rs,d4,d5,d6,d7,bl,blpol
LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);  


// Convert normal decimal numbers to binary coded decimal

byte decToBcd(byte val){
    return( (val/10*16) + (val%10) );
}

// Convert binary coded decimal to normal decimal numbers
byte bcdToDec(byte val){
    return( (val/16*10) + (val%16) );
}

void setup(){
    Wire.begin();
    Serial.begin(115200);
    // set the initial time here:
    // DS3231 seconds, minutes, hours, day, date, month, year odkomentovat další řádek pro nastavení času a data - zadat aktuální!!!!!
     setDS3231time(30,51,14,3,5,5,15);
    
     lcd.begin(20,4); // pocet znaku, pocet radku
     lcd.clear();
  lcd.backlight(); // zapni podsvetleni  
}

void setDS3231time(byte second, byte minute, byte hour, byte dayOfWeek, byte dayOfMonth, byte month, byte year){
    // sets time and date data to DS3231
    Wire.beginTransmission(DS3231_I2C_ADDRESS);
    Wire.write(0); // set next input to start at the seconds register
    Wire.write(decToBcd(second)); // set seconds
    Wire.write(decToBcd(minute)); // set minutes
    Wire.write(decToBcd(hour)); // set hours
    Wire.write(decToBcd(dayOfWeek)); // set day of week (1=Sunday, 7=Saturday)
    Wire.write(decToBcd(dayOfMonth)); // set date (1 to 31)
    Wire.write(decToBcd(month)); // set month
    Wire.write(decToBcd(year)); // set year (0 to 99)
    Wire.endTransmission();
}

void readDS3231time(byte *second, byte *minute, byte *hour, byte *dayOfWeek, byte *dayOfMonth, byte *month, byte *year){
    Wire.beginTransmission(DS3231_I2C_ADDRESS);
    Wire.write(0); // set DS3231 register pointer to 00h
    Wire.endTransmission();
    Wire.requestFrom(DS3231_I2C_ADDRESS, 7);
    // request seven bytes of data from DS3231 starting from register 00h
    *second = bcdToDec(Wire.read() & 0x7f);
    *minute = bcdToDec(Wire.read());
    *hour = bcdToDec(Wire.read() & 0x3f);
    *dayOfWeek = bcdToDec(Wire.read());
    *dayOfMonth = bcdToDec(Wire.read());
    *month = bcdToDec(Wire.read());
    *year = bcdToDec(Wire.read());
}

void displayTime(){
    byte second, minute, hour, dayOfWeek, dayOfMonth, month, year;
    // retrieve data from DS3231
    readDS3231time(&second, &minute, &hour, &dayOfWeek, &dayOfMonth, &month, &year);
    // send it to the serial monitor
    Serial.print(hour, DEC);
     lcd.setCursor(0,0);
  lcd.print(hour, DEC);
    // convert the byte variable to a decimal number when displayed
    Serial.print(":");
    lcd.print(":");
    if (minute<10){
        Serial.print("0");
        lcd.print("0");
    }
    Serial.print(minute, DEC);
    lcd.print(minute, DEC);
    
    Serial.print(":");
     lcd.print(":");
    if (second<10){
        Serial.print("0");
        lcd.print("0");
    }
    Serial.print(second, DEC);
    lcd.print(second, DEC);
    Serial.print(" ");
    lcd.print(" ");
    Serial.print(dayOfMonth, DEC);
    lcd.print(dayOfMonth, DEC);
    Serial.print("/");
    lcd.print("/");
    Serial.print(month, DEC);
    lcd.print(month, DEC);
    Serial.print("/");
    lcd.print("/");
    Serial.print(year, DEC);
    lcd.print(year, DEC);
    lcd.setCursor(0,1);
    Serial.print(" Day of week: ");
    lcd.print(" Day of week: ");
    lcd.setCursor(0,2);
    switch(dayOfWeek){
        case 1:
            Serial.println("Sunday");
            lcd.print("Sunday");
            break;
        case 2:
            Serial.println("Monday");
            lcd.print("Monday");
            break;
        case 3:
            Serial.println("Tuesday");
            lcd.print("Tuesday");
            break;
        case 4:
            Serial.println("Wednesday");
            lcd.print("Wednesday");
            break;
        case 5:
            Serial.println("Thursday");
            lcd.print("Thursday");
            break;
        case 6:
            Serial.println("Friday");
            lcd.print("Friday");
            break;
        case 7:
            Serial.println("Saturday");
            lcd.print("Saturday");
            break;
    }
 
    lcd.setCursor(0,3);   
    lcd.print("01234567890123456789");
}

void loop(){
    displayTime(); // display the real-time clock data on the Serial Monitor,
    delay(1000); // every second
}