;**********************************************************************
;   This file is a basic code template for assembly code generation   *
;   on the PIC16F628A. 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: P16F628A.INC                                     *
;                                                                     *
;**********************************************************************
;                                                                     *
;    Notes:                                                           *
;                                                                     *
;**********************************************************************

	list      p=16f628A           ; list directive to define processor
	#include <p16F628A.inc>       ; processor specific variable definitions

	errorlevel  -302              ; suppress message 302 from list file

	__CONFIG   _CP_OFF & _DATA_CP_OFF & _LVP_OFF & _BOREN_OFF & _MCLRE_ON & _WDT_OFF & _PWRTE_ON & _INTOSC_OSC_NOCLKOUT 

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




;***** VARIABLE DEFINITIONS
w_temp        EQU     0x7E        ; variable used for context saving 
status_temp   EQU     0x7F        ; variable used for context saving





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

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


	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

	goto	main		  ;loop forever, remove this instruction, for test only


; initialize eeprom locations

	ORG	0x2100
	DE	0x00, 0x01, 0x02, 0x03


	END                       ; directive 'end of program'