引脚说明

GND ------ 地线  VCC ------ 电源（5V or 3.3v 电源不同显示效果有点差别） SDA ------ I2C 数据线 SCL ------ I2C 时钟线  

接线方法

LCD1602 i2c模块                         Ardunio Uno   GND                           <------>        GND接地线 VCC                           <------>         5V 接电源 SDA                            <------>         A4 SCL                            <------>         A5 按键模块   K6 （set端口）     <------>     7 K7  （加）   <------>     6 K8  （减）      <------>     5 需要用到LCD1602 I2C的库，下载地址是 https://github.com/marcoschwartz/LiquidCrystal_I2C 程序如下：     #include
#include //引用I2C库
 
//设置LCD1602设备地址，这里的地址是0x3F，一般是0x20，或者0x27，具体看模块手册
LiquidCrystal_I2C lcd(0x3F,16,2);  
 #define choose  7   //选择端口
#define add  6      //加
#define minus  5    //减
unsigned long seconds;
int s = 0, m = 0, h = 0, d = 0, mon = 0, y = 0;   //时间进位
int second = 0, minute = 0, hour = 0, day = 0, month = 0, year = 0;  //当前时间
int SECOND = 0, MINUTE = 0, HOUR = 0, DAY = 0, MONTH = 0, YEAR = 0;  //初始时间
int chose = 0, ButtonDelay = 10;
void setup(){    
    for(int i = 6;i <= 9; i++){
       pinMode(i,OUTPUT);  
    }          
    digitalWrite(add, HIGH);
    digitalWrite(minus, HIGH);
    digitalWrite(choose, HIGH);  
    lcd.init();   //初始化LCD1602
    lcd.backlight();             //设置LCD背景等亮
    set(2018, 7, 25, 12, 30, 50);
}
 
/** 格式化输出  */
void FormatDisplay(int col, int row,int num){   
    lcd.setCursor(col, row);
    if(num < 10){
        lcd.print("0");
    }   
    lcd.print(num);   
}
 
/** 计算时间 */
void time(){   
    second = (SECOND + seconds) % 60;   //计算秒
    m = (SECOND + seconds) / 60;        //分钟进位
    FormatDisplay(6,1,second);
 
    minute = (MINUTE + m) % 60;  //计算分钟
    h = (MINUTE + m) / 60;       //小时进位
    FormatDisplay(3,1,minute);      
 
    hour = (HOUR + h) % 24;   //计算小时
    d = (HOUR + h) / 24;      //天数进位
    FormatDisplay(0,1,hour);
 
    lcd.setCursor(2, 1);   lcd.print(":");   
    lcd.setCursor(5, 1);   lcd.print(":");  
}
 
/** 根据年月计算当月天数 */
int Days(int year, int month){   
    int days = 0;
    if(month != 2){     
        switch(month){       
            case 1: case 3: case 5: case 7: case 8: case 10: case 12: days = 31;  break;
            case 4: case 6: case 9: case 11:  days = 30;  break;
        }
    }
    else{   //闰年    
        if(year % 4 == 0 && year % 100 != 0 || year % 400 == 0){
            days = 29;
        }   
        else{
            days = 28;   
        }     
    }  
    return days;   
}
 
/** 计算当月天数 */
void Day(){      
    int days = Days(year,month);
    int days_up;
    if(month == 1){
        days_up = Days( year - 1, 12 );
    } else{
        days_up = Days( year, month - 1 );
    }  
 
    day = (DAY + d) % days;
    if(day == 0){
        day = days;    
    }   
    if((DAY + d) == days + 1){   
        DAY -= days;
        mon++;
    }
    if((DAY + d) == 0){
        DAY += days_up;
        mon--;
    }
    FormatDisplay(8,0,day);
}
 
/** 计算月份 */
void Month(){   
    month = ( MONTH + mon ) % 12;
    if(month == 0){
        month = 12;
    }  
    y = (MONTH + mon - 1) / 12;
    FormatDisplay(5,0,month);
    lcd.setCursor(7, 0);   
    lcd.print('-');
}
 
/** 计算年份 */
void Year(){     
    year = (YEAR + y) % 9999;
    if(year == 0){
        year = 9999;
    }
    lcd.setCursor(0, 0);
    if(year < 1000){
        lcd.print("0");
    }
    if(year < 100){
        lcd.print("0");
    }
    if(year < 10) {
        lcd.print("0");
    }
    lcd.print(year);
    lcd.setCursor(4, 0);   
    lcd.print('-');
}
 
/** 根据年月日计算星期几 */
void Week(int y,int m, int d){        
    if(m == 1) m = 13;
    if(m == 2) m = 14;
    int week = (d+2*m+3*(m+1)/5+y+y/4-y/100+y/400)%7+1;
    String weekstr = "";
    switch(week){     
        case 1: weekstr = "Mon. ";   break;
        case 2: weekstr = "Tues. ";  break;
        case 3: weekstr = "Wed. ";   break;
        case 4: weekstr = "Thur. ";  break;
        case 5: weekstr = "Fri. ";   break;
        case 6: weekstr = "Sat. ";   break;
        case 7: weekstr = "Sun. ";   break;
    }    
    lcd.setCursor(11, 0);  lcd.print(weekstr);
}
 
/** 显示时间、日期、星期  */
void Display(){  
   time();
   Day();  
   Month();
   Year();
   Week(year,month,day);  
}
 
/** 显示光标 */
void DisplayCursor(int rol, int row){
    lcd.setCursor(rol, row);   
    lcd.cursor();
    delay(100);     
    lcd.noCursor();
    delay(100);    
}
 
/** 设置初始时间 */
void set(int y, int mon, int d, int h, int m, int s){
    YEAR = y;
    MONTH = mon;
    DAY = d;  
    HOUR = h;
    MINUTE = m;
    SECOND = s;  
}
 
/** 通过按键设置时间 */
void Set_Time(int rol, int row, int &Time){
   DisplayCursor(rol, row);
   if(digitalRead(add) == LOW){
        delay(ButtonDelay);
        if(digitalRead(add) == LOW){
            Time ++;
        }           
        Display();      
   }  
   if(digitalRead(minus) == LOW){
        delay(ButtonDelay);
        if(digitalRead(minus) == LOW){
            Time --;
        }           
        Display();  
    }  
}
 
/** 按键选择 */
void Set_Clock(){
    if(digitalRead(choose)==LOW){     
        lcd.setCursor(9, 1);  lcd.print("SetTime");
        while(1){       
            if(digitalRead(choose)==LOW){
                delay(ButtonDelay);
                if(digitalRead(choose)==LOW){
                    chose++;  
                }             
            }
            seconds = millis()/1000;
            Display();
            if(chose == 1){
                Set_Time(1, 1, HOUR);      //SetHour
            }else if(chose == 2){
                Set_Time(4, 1, MINUTE);    //SetMinute
            }else if(chose == 3){
                Set_Time(7, 1, SECOND);    //SetSecond
            }else if(chose == 4){
                Set_Time(9, 0, DAY);       //SetDay
            }else if(chose == 5){
                Set_Time(6, 0, MONTH);    // SetMonth
            }else if(chose == 6){           
                Set_Time(3, 0, YEAR);      //SetYear
            }else if(chose >= 7){
                chose = 0;
                lcd.clear();
                break;
            }
        }
    }  
}
 
void loop(){
    seconds = millis()/1000;    //获取单片机当前运行时间
    Display();       //显示时间
    Set_Clock();     //设置时间  
}