Và đây là code:
";Lap trinh: Tran Hong Cam
;Ngay 30/10/2010
;CT nay lam sang LEDs gan o PORT B, dong thoi kiem tra dac tinh chan RB3
processor 16F877A
include <P16F877A.inc>
__CONFIG _CP_OFF&_WDT_OFF&_BODEN_OFF&_PWRTE_ON&_XT_OSC&_WRT _OFF&_LVP_ON&_CPD_OFF
;Bat dau CT
ORG 0x000
GOTO START
;Khoi tao PORT B la cong xuat du lieu
ORG 0x005
START
BCF STATUS,RP1
BSF STATUS,RP0
CLRF TRISB
;Xuat du lieu ra PORT B
BCF STATUS,RP0
MOVLW b'11111111'
MOVWF PORTB
LOOP
GOTO LOOP
END "