Hỏi về EEPROM 24c256

[dong08101991]

em dang lam giao tiep giua 16f877a voi 24c256 ghi va doc xuat ra cong com.nhung sao moi lan xuat ra thi no hien tren mang hinh la ff chu ko hien ra du lieu em ghi vao epprom.xim cac anh giup do?day la code em ghi
#include <16f877a.h>
#include <2402.c>
#fuses nowdt, noprotect, nolvp, xt, put
#use delay(clock = 4000000)
#use fast_io(b)
#use rs232 (baud=9600 , parity=n , xmit=pin_C6 , rcv=pin_C7 )
#byte portb = 0x06
#bit b0 = portb.0
#bit b1 = portb.1
int8 x,b;
void ghi ();
void doc ();
void main()
{
set_tris_b(0b00000011);
init_ext_eeprom();
while (1) {
if (b0 == 0) {
ghi ();
}
else {
if (b1==0) {
doc ();}
else {}}
}}
void ghi()
{
loop:
if (b0 == 1) {
write_ext_eeprom(0x0a, 2);}
else {
goto loop;}
}
void doc()
{
loop1:
if (b1 == 1){
x = read_ext_eeprom(0x0a);
printf("data ghi: %x \r ",x );
}
else {
goto loop1;}
}