Datasheet

Table Of Contents
© 2006 Microchip Technology Inc. DS41159E-page 203
PIC18FXX8
EXAMPLE 19-1: WIN AND ICODE BITS USAGE IN INTERRUPT SERVICE ROUTINE TO ACCESS
TX/RX BUFFERS
; Save application required context.
; Poll interrupt flags and determine source of interrupt
; This was found to be CAN interrupt
; TempCANCON and TempCANSTAT are variables defined in Access Bank low
MOVFF CANCON, TempCANCON ; Save CANCON.WIN bits
; This is required to prevent CANCON
; from corrupting CAN buffer access
; in-progress while this interrupt
; occurred
MOVFF CANSTAT, TempCANSTAT ; Save CANSTAT register
; This is required to make sure that
; we use same CANSTAT value rather
; than one changed by another CAN
; interrupt.
MOVF TempCANSTAT, W ; Retrieve ICODE bits
ANDLW b’00001110’
ADDWF PCL, F ; Perform computed GOTO
; to corresponding interrupt cause
BRA NoInterrupt ; 000 = No interrupt
BRA ErrorInterrupt ; 001 = Error interrupt
BRA TXB2Interrupt ; 010 = TXB2 interrupt
BRA TXB1Interrupt ; 011 = TXB1 interrupt
BRA TXB0Interrupt ; 100 = TXB0 interrupt
BRA RXB1Interrupt ; 101 = RXB1 interrupt
BRA RXB0Interrupt ; 110 = RXB0 interrupt
; 111 = Wake-up on interrupt
WakeupInterrupt
BCF PIR3, WAKIF ; Clear the interrupt flag
;
; User code to handle wake-up procedure
;
;
; Continue checking for other interrupt source or return from here
NoInterrupt
; PC should never vector here. User may
; place a trap such as infinite loop or pin/port
; indication to catch this error.
ErrorInterrupt
BCF PIR3, ERRIF ; Clear the interrupt flag
; Handle error.
RETFIE
TXB2Interrupt
BCF PIR3, TXB2IF ; Clear the interrupt flag
GOTO AccessBuffer
TXB1Interrupt
BCF PIR3, TXB1IF ; Clear the interrupt flag
GOTO AccessBuffer
TXB0Interrupt
BCF PIR3, TXB0IF ; Clear the interrupt flag
GOTO AccessBuffer
RXB1Interrupt
BCF PIR3, RXB1IF ; Clear the interrupt flag
GOTO Accessbuffer