PIC单片机的读写93C46程序
; THIS ROUTE IS USED FOR 93C46 (Configue as
; 16 bits organizatio) READ & WRITE ROUTE
RA EQU 5
RB EQU 6
BIT-COUNT EQU
DATA_HI EQU 10H ; HI half of words
DATA_LO EQU 11H ; LO half of words
ROM_AD EQU 12H ; the address of 93c46
TEMR EQU 13H ;
BIT_COUNT EQU 14H
;
CM_EWEN EQU 30H
CM_EWDS EQU 0H
;RA
CS EQU 0
SK EQU 1
DI EQU 2
;---------------
;used transmiting the first bits in commands
START_BITS
BCF RA,SK
NOP
BSF RA,CS
NOP
BSF RA,DI
NOP
BSF RA,SK
NOP
BCF RA,SK
RETLW 0
;------------------
;the route of transmitting a byte
TRMIT ;
MOVLW 8
MOVWF BIT_COUNT
TRM0
BCF 3,0
BCF RA,SK
RLF TEMR
BTFSS 3,0
GOTO ^+3
BSF RA,DI
GOTO ^+2
BCF RA,DI
NOP
BSF RA,SK
DECFSZ BIT_COUNT
GOTO TRM0
RETLW 0H
;---------------------
;the route of receiving a byte
RECEIVE
MOVLW 8H
MOVWF BIT_COUNT
CLRF TEMR
RV0
BSF RA,SK
NOP
NOP
BSF 3,0
BCF RA,SK
NOP
BTFSS RA,DO
BCF 3,0
RLF TEMR
DECFSZ BIT_COUNT
GOTO RV0
RETLW 0H
;=============================
; read a word data.
; the data in ROM_AD is the address of
; the word, which come from main route
RD_ROM
MOVLW 080H
IORWF ROM_AD
MOVFW ROM_AD
MOVWF TEMR
CALL START_BITS
CALL TRMIT
RC_DA
NOP
BCF RA,SK
NOP
BTFSC RA,DO
RETLW 0FFH
CALL RECEIVE
MOVFW TEMR
MOVWF DATA_HI
CALL RECEIVE
MOVFW TEMR
MOVWF DATA_LO
BCF RA,CS
RETLW 0
;=============================
; write a word data.
; the data in ROM_AD is the address of
; the word, which come from main route
WRT
MOVLW 40H
IORWF ROM_AD
MOVFW ROM_AD
MOVWF TEMR
CALL START_BITS
CALL TRMIT
MOVFW DATA_HI
MOVWF TEMR
CALL TRMIT
MOVFW DATA_LO
MOVWF TEMR
BCF RA,CS
RETLW 0H
;-----------------------------
EWEN
MOVLW CM_EWEN
GOTO EWDS+1
EWDS
MOVLW CM_EWDS
MOVWF ROM_AD
MOVFW ROM_AD
MOVWF TEMR
CALL START_BITS
CALL TRMIT
BCF RA,CS
RETLW 0H
