xí quên cái code (cái này em copy lại trong tut thôi)
processor 16f877a ; KHAI BAO CHIP
include <p16f877a.inc> ; KHAI BAO HEADER FILE
__CONFIG _CP_OFF&_WDT_OFF&_BODEN_OFF&_PWRTE_ON&_XT_OSC&_WRT _OFF&_LVP_OFF&_CPD_OFF ;KHAI BAO CONFIG
;-----------------------------------------------------------------------
;KHOI TAO CAC BIEN
;-----------------------------------------------------------------------
count1 EQU 0X20
counta EQU 0X21
countb EQU 0x22
;=====================================
;CHUONG TRINH CHINH
;=====================================
ORG 0X000
GOTO start
start
BCF STATUS, RP1 ;
BSF STATUS, RP0 ; CHON BANK 1
CLRF TRISB ; KHOI TAO PORTB OUTPUT
BCF STATUS, RP0 ; CHON BANK 0
loop
MOVLW 0XFF ;
MOVWF PORTB ; BAT TAT CA CAC LED O PORTB
CALL delay_100ms ; GOI CHUONG TRINH CON delay_100ms
CLRF PORTB ; TAT HET LED PORTB
CALL delay_100ms ; GOI CHUONG TRINH CON delay_100ms
GOTO loop ; THUC HIEN LAI TU DAU
;------------------------------------------------
;chuong trinh con
;------------------------------------------------
delay_100ms ; NHAN BAT DAU CHUONG TRINH CON
MOVLW d'100'
MOVWF count1
d1
MOVLW d'199'
MOVWF counta
MOVLW d'1'
MOVWF countb
delay_0
DECFSZ counta,1
GOTO $+2
DECFSZ countb,1
GOTO delay_0
DECFSZ count1,1
GOTO d1
RETURN ; KET THUC CHUONG TRINH CON
END