PIC Hello World
From On-signal: Projects & Research
The assembly code for a simple "Hello world", a 4-led walking-light ("looplicht"), programmed on a PIC 16F628A.
;;; ************************************************************
;;; LED walking light with 4 leds
;;; Arjan Scherpenisse <arjan@scherpenisse.net>, jan 2009
;;; This code is released in the public domain.
;;; ************************************************************
LIST P=16F628A, R=DEC ; Use the PIC16F628 and decimal system
#include "P16F628A.INC" ; Include header file
__config _INTRC_OSC_NOCLKOUT & _LVP_OFF & _WDT_OFF & _PWRTE_ON & _BODEN_ON
CBLOCK 0x20 ; Declare variable addresses starting at 0x20
Loop1,Loop2
ENDC
;
; -----------
; INITIALIZE
; -----------
;
ORG 0x000 ; Program starts at 0x000
CLRF PORTA ; Initialize port A
CLRF PORTB ; Initialize port B
BSF STATUS,RP0 ; RAM bank 1
CLRF TRISA ; All pins port A output
CLRF TRISB ; All pins port B output
BCF STATUS,RP0 ; RAM bank 0
;
; ------------------------
; FUNCTION OF PORT A PINS
; ------------------------
;
MOVLW 7
MOVWF CMCON ; Comparators off, all pins digital I/O
;
; ----------
; MAIN LOOP
; ----------
;
Main
BCF PORTA,0
BCF PORTA,1
BCF PORTA,2
BSF PORTA,3
CALL delay
BCF PORTA,0
BCF PORTA,1
BSF PORTA,2
BCF PORTA,3
CALL delay
BCF PORTA,0
BSF PORTA,1
BCF PORTA,2
BCF PORTA,3
CALL delay
BSF PORTA,0
BCF PORTA,1
BCF PORTA,2
BCF PORTA,3
CALL delay
GOTO Main
;
; ---------------
; DELAY 250 MSEC
; ---------------
;
delay MOVLW 250
MOVWF Loop1
Outer MOVLW 200
MOVWF Loop2
Inner NOP
NOP
DECFSZ Loop2,F
GOTO Inner ; Inner loop = 5 usec.
DECFSZ Loop1,F
GOTO Outer
RETURN
END
