Practica 1 - Sistemas embebidos

;**********************************************************************
;   This file is a basic code template for assembly code generation   *
;   on the PIC16F877A. This file contains the basic code              *
;   building blocks to build upon.                                    *  
;                                                                     *
;   Refer to the MPASM User's Guide for additional information on     *
;   features of the assembler (Document DS33014).                     *
;                                                                     *
;   Refer to the respective PIC data sheet for additional             *
;   information on the instruction set.                               *
;                                                                     *
;**********************************************************************
;                                                                     *
;    Filename:	    xxx.asm                                           *
;    Date:                                                            *
;    File Version:                                                    *
;                                                                     *
;    Author:                                                          *
;    Company:                                                         *
;                                                                     * 
;                                                                     *
;**********************************************************************
;                                                                     *
;    Files Required: P16F877A.INC                                     *
;                                                                     *
;**********************************************************************
;                                                                     *
;    Notes:                                                           *
;                                                                     *
;**********************************************************************


	list		p=16f877A	; list directive to define processor
	#include	<p16f877A.inc>	; processor specific variable definitions
	
	__CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_ON & _XT_OSC & _WRT_OFF & _LVP_OFF & _CPD_OFF

; '__CONFIG' directive is used to embed configuration data within .asm file.
; The lables following the directive are located in the respective .inc file.
; See respective data sheet for additional information on configuration word.






;***** VARIABLE DEFINITIONS}
var5		EQU 0x77
sum			EQU 0X78
contador 	EQU 0X79
VAR1 		EQU 0X7C
VAR2 		EQU 0X7A
VAR3 		EQU 0X7B

w_temp		EQU	0x7D		; variable used for context saving 
status_temp	EQU	0x7E		; variable used for context saving
pclath_temp	EQU	0x7F		; variable used for context saving			






;**********************************************************************
	ORG     0x000             ; processor reset vector

	nop			  ; nop required for icd
  	goto    main              ; go to beginning of program


	ORG     0x004             ; interrupt vector location

	movwf   w_temp            ; save off current W register contents
	movf	STATUS,w          ; move status register into W register
	movwf	status_temp       ; save off contents of STATUS register
	movf	PCLATH,w	  ; move pclath register into w register
	movwf	pclath_temp	  ; save off contents of PCLATH register

; isr code can go here or be located as a call subroutine elsewhere

	movf	pclath_temp,w	  ; retrieve copy of PCLATH register
	movwf	PCLATH		  ; restore pre-isr PCLATH register contents
	movf    status_temp,w     ; retrieve copy of STATUS register
	movwf	STATUS            ; restore pre-isr STATUS register contents
	swapf   w_temp,f
	swapf   w_temp,w          ; restore pre-isr W register contents
	retfie                    ; return from interrupt



main

; remaining code goes here

	CLRF STATUS
	CLRF PORTB
	
	BSF STATUS, RP0 
	MOVLW 0X00
	MOVWF TRISB
	CLRF STATUS
	
	
init:

	bcf STATUS , C
	MOVLW 0X07
	MOVWF contador

	
	CALL sub_delay
	MOVLW 0X01
	MOVWF var5
	movf var5,w
	movwf PORTB

rotar:
	CALL sub_delay
	RLF var5 , f
	movf var5,w
	movwf PORTB
	DECFSZ contador, f
GOTO rotar
GOTO init
	



sub_delay:

	MOVLW 0X04
	MOVWF VAR3
	
	MOVLW 0XCD
	MOVWF VAR2
	
	MOVLW 0XFF
	MOVWF VAR1
	
del:
nop
	DECFSZ VAR1 , F
	GOTO del
	DECFSZ VAR2 , F
	GOTO del
	DECFSZ VAR3 , F
	GOTO del

RETURN









	END                       ; directive 'end of program'