Microcontrollers Lab 3

lab3EENG3040.ASM

;******************************************************
;PIC Configuration for PIC16F887
#include "p16F887.inc"

; CONFIG1
; __config 0x2032
 __CONFIG _CONFIG1, _FOSC_HS & _WDTE_OFF & _PWRTE_OFF & _MCLRE_ON & _CP_ON & _CPD_ON & _BOREN_OFF & _IESO_OFF & _FCMEN_OFF & _LVP_OFF
; CONFIG2
; __config 0x3FFF
 __CONFIG _CONFIG2, _BOR4V_BOR40V & _WRT_OFF
;******************************************************

PREV    EQU 20H     ;Used to track whether previous value of button was 1 or 0
COUNT   EQU 21H     ;Keeps track of how many button presses have happened
DCOUNT  EQU 22H     ;Use for delay

;******************************************************
  ORG 000H
  GOTO MAIN
  ORG 0008H
MOVLW 21

;*******************************************************
MAIN
  BSF STATUS,RP1             ;change to bank 3
  BSF STATUS,RP0

  CLRF ANSEL                 ;Using all digital mode, turns off analog
  CLRF ANSELH                ;Make all analog ports digital

  BCF STATUS,RP1             ;change to correct bank to configure TRIS registers
                             ;MAKE RA0 OUTPUT, RB0 INPUT, PORTC AND PORTD ALL OUTPUTS
  MOVLW 0FEH
  MOVWF TRISA
  CLRF  TRISB
  COMF  TRISB,1
  CLRF  TRISC
  CLRF  TRISD

  BCF  STATUS,RP0          ;return to bank 0
  CLRF PORTB               ;CLEAR PORTB, PORTC, PREV, AND COUNT
  CLRF PORTC
  CLRF PREV
  CLRF COUNT
LOOP
    MOVF    COUNT,0        ;MOVE COUNT INTO W 
    CALL    TABLE          ;Look up value for 7 segment display to show count
    MOVWF   PORTD          ;PUT RETURNED VALUE (now in W) ON PORTD
    BCF     PORTA,0        ;CLEAR RA0, CALL DELAY, SET RA0
    CALL    DELAY
    BSF     PORTA,0
    BTFSC   PORTB,0        ;ADD BIT TEST ON RB0
    GOTO    RB0HI          ;GO HERE IF RB0 IS 1
    GOTO    RB0LO          ;GO HERE IF RB0 IS 0
RB0HI                      ;ADD BIT TEST TO SEE IF BIT 0 OF PREV WAS LOW, THIS INDICATES RISING EDGE
        BTFSS   PREV,0
        CALL    INCCNT
        BSF     PREV,0     ;SET THIS BIT TO TRACK HISTORY
        GOTO    NEXT
RB0LO   CALL    DELAY
        BCF     PREV,0     ;CLEAR THIS BIT TO TRACK HISTORY
NEXT    GOTO    LOOP       ;INFINITE LOOP
  
INCCNT  
                           ;INCREMENT COUNT
   INCF COUNT
                           ;CHECK IF VALUE OF COUNT IS 10 AND TO RESET COUNT TO 0 IF IT EQUALS 10
   MOVLW 0x0A
   XORWF COUNT,0
   BTFSC STATUS,Z
   CLRF  COUNT
                           ;WRITE COUNT TO PORTC (via W)
   MOVF  COUNT,0
   MOVWF PORTC
   CALL  DELAY
    RETURN

DELAY 
    MOVLW   0FFH
    MOVWF   DCOUNT
DLOOP    DECFSZ  DCOUNT
         GOTO   DLOOP
         RETURN

TABLE 
 ADDWF   PCL,1                ;instruction register add excursion address
 RETLW   0C0H                 ;the code for 0( the common LED is anode)
 RETLW   0F9H                 ;the code for 1
 RETLW   0A4H                 ;the code for 2
 RETLW   0B0H                 ;the code for 3
 RETLW   99H                  ;the code for 4
 RETLW   92H                  ;the code for 5
 RETLW   82H                  ;the code for 6
 RETLW   0F8H                 ;the code for 7
 RETLW   80H                  ;the code for 8
 RETLW   90H                  ;the code for 9
 END