PIC Vietnam - help!! lcd bị giật

em đang làm đồ án ds1307 hiển thị lcd nhưng sao lcd nó bị giật.
;////////////////// đây là code//////////
#include <16F877A.h>
#include <def_877a.h>
#FUSES NOWDT, HS, PUT, NOPROTECT
#use DELAY(clock=12000000)
#use i2c(master,fast,sda=PIN_C4,scl=PIN_C3)
// Hai chan RC4 RC3 dung de giao tiep i2c
#define giay_ch 0x8b
#define giay_dv 0x8c
#define phut_ch 0x88
#define phut_dv 0x89
#define gio_ch 0x85
#define gio_dv 0x86
#define ngay_ch 0xc5
#define ngay_dv 0xc6
#define thang_ch 0xc8
#define thang_dv 0xc9
#define nam_ch 0xcb
#define nam_dv 0xcc
#define RS RB5
#define RW RB6
#define E RB7
#define LCD PORTD
int8 sec,min,hour,date,month,year,day;
int8 sec1,sec2,min1,min2,hour1,hour2,date1,date2,month1 ,month2,year1,year2;

void commwrite();
void datawrite();
void setup_lcd();
void update_time();
void bin_bcd();
void ht_lcd_text();
void ht_lcd_data();

void commwrite() //Ham yeu cau goi lenh de dieu khien LCD
{
RS=0;
RW=0;
E=1;
E=0;
delay_ms(1);
}
void datawrite() //Ham yeu cau goi du lieu hien thi len LCD
{
RS=1;
RW=0;
E=1;
E=0;
delay_ms(1);
}
void setup_lcd() //Ham cai dat che do cho LCD
{
LCD=0x01; //Xoa man hinh LCD
commwrite();
LCD=0x38; //Cai dat LCD hien thi 2 dong
commwrite();
LCD=0x0C; //Dieu khien hien thi
commwrite();
}

void update_time()
{
i2c_start();
i2c_write(0xD0); //Gui lenh ghi du lieu */dia chi DS1307<<1|write=0 bat dau ghi
i2c_write(0x07); //thiet lap d/c - thanh ghi thiet lap trang thai lam viec ds1307
i2c_write(0x10); //tao f=1hz tai chan 7 (ds1307)
i2c_stop(); //|restar i2c
i2c_start(); //|

i2c_write(0xD0);
i2c_write(0x00);
i2c_start();
i2c_write(0xD1); //dia chi DS1307<<1|read=1 bat dau doc
sec = i2c_read();
min = i2c_read();
hour = i2c_read();
day = i2c_read();
date = i2c_read();
month = i2c_read();
year = i2c_read(0);
i2c_stop();
}
void bin_bcd()
{
sec1=sec & 0x0F;
sec2=sec & 0x70;//convert to BCD SEC
sec2=sec2>>4;
sec1=sec1+0x30;//dua ve ma chuan de hien thi LCD
sec2=sec2+0x30;//dua ve ma chuan de hien thi LCD
min1=min & 0x0F;
min2=min & 0x70;//convert to BCD SEC
min2=min2>>4;
min1=min1+0x30;//dua ve ma chuan de hien thi LCD
min2=min2+0x30;//dua ve ma chuan de hien thi LCD
hour1=hour & 0x0F;
hour2=hour & 0x30;//convert to BCD SEC
hour2=hour2>>4;
hour1=hour1+0x30;//dua ve ma chuan de hien thi LCD
hour2=hour2+0x30;//dua ve ma chuan de hien thi LCD
//ngay
date1=date & 0x0F;
date2=date & 0x30;//convert to BCD SEC
date2=date2>>4;//dich 4bit cao xuong 4bit thap
date1=date1+0x30;//dua ve ma chuan de hien thi LCD
date2=date2+0x30;//dua ve ma chuan de hien thi LCD
//thang
month1=month & 0x0F;
month2=month & 0x10;//convert to BCD SEC
month2=month2>>4;//dich 4bit cao xuong 4bit thap
month1=month1+0x30;//dua ve ma chuan de hien thi LCD
month2=month2+0x30;//dua ve ma chuan de hien thi LCD
//nam
year1=year & 0x0F;
year2=year & 0xf0;//convert to BCD SEC
year2=year2>>4;//dich 4bit cao xuong 4bit thap
year1=year1+0x30;//dua ve ma chuan de hien thi LCD
year2=year2+0x30;//dua ve ma chuan de hien thi LCD
}
void ht_lcd_text()
{
setup_lcd();

LCD=0x80;
commwrite();
LCD=('T');
datawrite();
LCD=('i');
datawrite();
LCD=('m');
datawrite();
LCD=('e');
datawrite();
LCD=(':');
datawrite();
LCD=0x38;
commwrite();
LCD=0xC0;
commwrite();
LCD=('D');
datawrite();
LCD=('a');
datawrite();
LCD=('t');
datawrite();
LCD=('e');
datawrite();
LCD=(':');
datawrite();
}
void ht_lcd_data()
{
setup_lcd();

LCD=0x85;
commwrite();
LCD=(hour2);
datawrite();
LCD=(hour1);
datawrite();
LCD=(' ');
datawrite();
LCD=(min2);
datawrite();
LCD=(min1);
datawrite();
LCD=(' ');
datawrite();
LCD=(sec2);
datawrite();
LCD=(sec1);
datawrite();

LCD=0xC5;
commwrite();

LCD=(date2);
datawrite();
LCD=(date1);
datawrite();
LCD=('/');
datawrite();
LCD=(month2);
datawrite();
LCD=(month1);
datawrite();
LCD=('/');
datawrite();
LCD=(year2);
datawrite();
LCD=(year1);
datawrite();
}

void main()
{
trisa=0x00; // Cong A lam dau ra
trisb=0x01; // Cong B lam dau ra (tru RB0)
trisd=0x00; // Cong D lam dau ra

while(true)
{
update_time();
bin_bcd();
ht_lcd_text();
ht_lcd_data();
delay_ms(10);
}
}