Microchip Technology DM164134 Data Sheet

PIC18FXX8

DS41159E-page 204

EXAMPLE 19-1:

WIN AND ICODE BITS USAGE IN INTERRUPT SERVICE ROUTINE TO ACCESS
TX/RX BUFFERS (CONTINUED)

RXB0Interrupt

BCF

PIR3, RXB0IF

; Clear the interrupt flag

GOTO

AccessBuffer

; This is either TX or RX interrupt

; Copy CANCON.ICODE bits to CANSTAT.WIN bits

MOVF

CANCON, W

; Clear CANCON.WIN bits before copying

; new ones.

ANDLW

b’11110001’

; Use previously saved CANCON value to

; make sure same value.

MOVWF

CANCON

; Copy masked value back to TempCANCON

MOVF

TempCANSTAT, W

; Retrieve ICODE bits

ANDLW

b’00001110’

; Use previously saved CANSTAT value

; to make sure same value.

IORWF

CANCON

; Copy ICODE bits to WIN bits.

; Copy the result to actual CANCON

; Access current buffer…

; User code

; Restore CANCON.WIN bits

MOVF

CANCON, W

; Preserve current non WIN bits

ANDLW

b’11110001’

IORWF

TempCANCON, W

; Restore original WIN bits

MOVWF

CANCON

; Do not need to restore CANSTAT - it is read-only register.

; Return from interrupt or check for another module interrupt source