#include "RTClib.h"
#include <LiquidCrystal_I2C.h>
RTC_DS1307 rtc;
#define I2C_ADDR    0x27
#define LCD_COLUMNS 16
#define LCD_LINES   2
LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);
int butpos = 9;
int butneg = 8;
int oldvalpos = HIGH;
bool oldvalneg = HIGH;
void setup() {
  // put your setup code here, to run once:
    if (! rtc.begin()) {
    Serial.println("Couldn't find RTC");
    Serial.flush();
    abort();
  }
  lcd.init();
  lcd.backlight();
  pinMode(butpos, INPUT_PULLUP);
  pinMode(butneg, INPUT_PULLUP);
}
void loop() {
  // put your main code here, to run repeatedly:
  DateTime now = rtc.now();
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(now.hour(), DEC);
  lcd.print(":");
  lcd.print(now.minute(), DEC);
  lcd.print(":");
  lcd.print(now.second(), DEC);
  delay(500);
  if (digitalRead(butpos) != oldvalpos) {
    if (digitalRead(butpos)== LOW){
    DateTime newTime = DateTime(now.year(), now.month(), now.day(), now.hour(),
                              (now.minute() + 1) % 60, now.second()); // Увеличение минут
    rtc.adjust(newTime);
    }
    oldvalpos = digitalRead(butpos);
  }
  if (digitalRead(butneg) != oldvalneg) {
    if (digitalRead(butneg)== LOW){
    DateTime newTime = DateTime(now.year(), now.month(), now.day(), now.hour(),
                              (now.minute() - 1) % 60, now.second()); // уменьшение минут
    rtc.adjust(newTime);
    }
    oldvalneg = digitalRead(butneg);
  }
}