;******************************************************************************
; This file is a basic template for assembly code for a PIC18F4550. Copy *
; this file into your project directory and modify or add to it as needed. *
; *
; Refer to the MPASM User's Guide for additional information on the *
; features of the assembler. *
; *
; Refer to the PIC18Fx455/x550 Data Sheet for additional *
; information on the architecture and instruction set. *
; *
;******************************************************************************
; *
; Filename: *
; Date: *
; File Version: *
; *
; Author: *
; Company: *
; *
;******************************************************************************
; *
; Files Required: P18F4550.INC *
; *
;******************************************************************************
LIST P=18F4550 ;directive to define processor
#include <P18F4550.INC> ;processor specific variable definitions
;******************************************************************************
;Configuration bits
;Microchip has changed the format for defining the configuration bits, please
;see the .inc file for futher details on notation. Below are a few examples.
; Oscillator Selection:
CONFIG FOSC=INTOSCIO_EC, WDT=OFF, PWRT=ON, BOR=OFF, MCLRE=OFF, LPT1OSC=OFF, XINST=OFF
CONFIG LVP=OFF, VREGEN=OFF, PBADEN=OFF, DEBUG=OFF
;******************************************************************************
;Variable definitions
; These variables are only needed if low priority interrupts are used.
; More variables may be needed to store other special function registers used
; in the interrupt routines.
CBLOCK 0x080
WREG_TEMP ;variable used for context saving
STATUS_TEMP ;variable used for context saving
BSR_TEMP ;variable used for context saving
ENDC
CBLOCK 0x000
EXAMPLE ;example of a variable in access RAM
ENDC
;******************************************************************************
;EEPROM data
; Data to be programmed into the Data EEPROM is defined here
ORG 0xf00000
DE "Test Data",0,1,2,3,4,5
;******************************************************************************
;Reset vector
; This code will start executing when a reset occurs.
ORG 0x0000
goto Main ;go to start of main code
;******************************************************************************
;High priority interrupt vector
; This code will start executing when a high priority interrupt occurs or
; when any interrupt occurs if interrupt priorities are not enabled.
ORG 0x0008
bra HighInt ;go to high priority interrupt routine
;******************************************************************************
;Low priority interrupt vector and routine
; This code will start executing when a low priority interrupt occurs.
; This code can be removed if low priority interrupts are not used.
ORG 0x0018
movff STATUS,STATUS_TEMP ;save STATUS register
movff WREG,WREG_TEMP ;save working register
movff BSR,BSR_TEMP ;save BSR register
; *** low priority interrupt code goes here ***
movff BSR_TEMP,BSR ;restore BSR register
movff WREG_TEMP,WREG ;restore working register
movff STATUS_TEMP,STATUS ;restore STATUS register
retfie
;******************************************************************************
;High priority interrupt routine
; The high priority interrupt code is placed here to avoid conflicting with
; the low priority interrupt vector.
HighInt:
; *** high priority interrupt code goes here ***
retfie FAST
;******************************************************************************
;Start of main program
; The main program code is placed here.
Main:
; *** main code goes here ***
movlw b'01100010' ; set internal osc to 4 mhz
movwf OSCCON
; configure data port direction
clrf TRISD
checkWR:
btfsc EECON1, WR
goto checkWR
movlw 0x00 ; address in EEPROM
movwf EEADR
movlw 0x22 ; data to write 0x77 = 1111 0001
movwf EEDATA
bcf EECON1, EEPGD
bcf EECON1, CFGS
bsf EECON1, WREN
bcf INTCON, GIE ; disable interrupt
movlw 0x55
movwf EECON2
movlw 0xAA
movwf EECON2
bsf EECON1, WR
nop
nop
checkWRDone:
btfsc EECON1, WR
goto checkWRDone
bsf INTCON, GIE
bcf EECON1, WREN
; reading the data for verification
movlw 0x00
movwf EEADR
bcf EECON1, EEPGD
bcf EECON1, CFGS
bsf EECON1, RD
movf EEDATA, w
movwf PORTD
wait:
goto wait
end
;******************************************************************************
;End of program