Datasheet

 2010-2012 Microchip Technology Inc. DS39977F-page 169
PIC18F66K80 FAMILY
10.9 Context Saving During Interrupts
During interrupts, the return PC address is saved on
the stack. Additionally, the WREG, STATUS and BSR
registers are saved on the Fast Return Stack.
If a fast return from interrupt is not used (see
Section 6.3 “Data Memory Organization”), the user
may need to save the WREG, STATUS and BSR regis-
ters on entry to the Interrupt Service Routine (ISR).
Depending on the user’s application, other registers
also may need to be saved.
Example 10-1 saves and restores the WREG, STATUS
and BSR registers during an Interrupt Service Routine.
EXAMPLE 10-1: SAVING STATUS, WREG AND BSR REGISTERS IN RAM
TABLE 10-1: SUMMARY OF REGISTERS ASSOCIATED WITH INTERRUPTS
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF
INTCON2 RBPU
INTEDG0 INTEDG1 INTEDG2 INTEDG3 TMR0IP INT3IP RBIP
INTCON3 INT2IP INT1IP INT3IE INT2IE INT1IE INT3IF INT2IF INT1IF
PIR1 PSPIP ADIF RC1IF TX1IF SSPIF TMR1GIF TMR2IF TMR1IF
PIR2 OSCFIF
— — — BCLIF HLVDIF TMR3IF TMR3GIF
PIR3
— — RC2IF TX2IF CTMUIF CCP2IF CCP1IF —
PIR4 TMR4IF EEIF CMP2IF CMP1IF
— CCP5IF CCP4IF CCP3IF
PIR5 IRXIF WAKIF ERRIF TXB2IF TXB1IF TXB0IF RXB1IF RXB0IF
PIE1 PSPIE ADIE RC1IE TX1IE SSPIE TMR1GIE TMR2IE TMR1IE
PIE2 OSCFIE
— — — BCLIE HLVDIE TMR3IE TMR3GIE
PIE3
— — RC2IE TX2IE CTMUIE CCP2IE CCP1IE —
PIE4 TMR4IE EEIE CCP2IE CMP1IE
— CCP5IE CCP4IE CCP3IE
PIE5 IRXIE WAKIE ERRIE TXB2IE TXB1IE TXB0IE RXB1IE RXB0IE
IPR1 PSPIP ADIP RC1IP TX1IP SSPIP TMR1GIP TMR2IP TMR1IP
IPR2 OSCFIP
— — — BCLIP HLVDIP TMR3IP TMR3GIP
IPR3
— — RC2IP TX2IP CTMUIP CCP2IP CCP1IP —
IPR4 TMR4IP EEIP CMP2IP CMP1IP
— CCP5IP CCP4IP CCP3IP
IPR5 IRXIP WAKIP ERRIP TXB2IP TXB1IP TXB0IP RXB1IP RXB0IP
RCON IPEN SBOREN CM
RI TO PD POR BOR
Legend: Shaded cells are not used by the interrupts.
MOVWF W_TEMP ; W_TEMP is in virtual bank
MOVFF STATUS, STATUS_TEMP ; STATUS_TEMP located anywhere
MOVFF BSR, BSR_TEMP ; BSR_TMEP located anywhere
;
; USER ISR CODE
;
MOVFF BSR_TEMP, BSR ; Restore BSR
MOVF W_TEMP, W ; Restore WREG
MOVFF STATUS_TEMP, STATUS ; Restore STATUS