PIC18F23K20-E/MLQTP MICROCHIP [Microchip Technology], PIC18F23K20-E/MLQTP Datasheet - Page 117

• Manufacturer Part Number: PIC18F23K20-E/MLQTP
• Description: 28/40/44-Pin Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

9.9
External interrupts on the RB0/INT0, RB1/INT1 and
RB2/INT2 pins are edge-triggered. If the corresponding
INTEDGx bit in the INTCON2 register is set (= 1), the
interrupt is triggered by a rising edge; if the bit is clear,
the trigger is on the falling edge. When a valid edge
appears on the RBx/INTx pin, the corresponding flag
bit, INTxF, is set. This interrupt can be disabled by
clearing the corresponding enable bit, INTxE. Flag bit,
INTxF, must be cleared by software in the Interrupt
Service Routine before re-enabling the interrupt.
All external interrupts (INT0, INT1 and INT2) can wake-
up the processor from Idle or Sleep modes if bit INTxE
was set prior to going into those modes. If the Global
Interrupt Enable bit, GIE, is set, the processor will
branch to the interrupt vector following wake-up.
Interrupt priority for INT1 and INT2 is determined by the
value contained in the interrupt priority bits, INT1IP and
INT2IP of the INTCON3 register. There is no priority bit
associated with INT0. It is always a high priority inter-
rupt source.
EXAMPLE 9-1:
© 2007 Microchip Technology Inc.
MOVWF
MOVFF
MOVFF
;
; USER ISR CODE
;
MOVFF
MOVF
MOVFF
INTn Pin Interrupts
W_TEMP
STATUS, STATUS_TEMP
BSR, BSR_TEMP
BSR_TEMP, BSR
W_TEMP, W
STATUS_TEMP, STATUS
SAVING STATUS, WREG AND BSR REGISTERS IN RAM
Advance Information
; W_TEMP is in virtual bank
; STATUS_TEMP located anywhere
; BSR_TMEP located anywhere
; Restore BSR
; Restore WREG
; Restore STATUS
9.10
In 8-bit mode (which is the default), an overflow in the
TMR0 register (FFh → 00h) will set flag bit, TMR0IF. In
16-bit mode, an overflow in the TMR0H:TMR0L regis-
ter pair (FFFFh → 0000h) will set TMR0IF. The interrupt
can be enabled/disabled by setting/clearing enable bit,
TMR0IE of the INTCON register. Interrupt priority for
Timer0 is determined by the value contained in the
interrupt priority bit, TMR0IP of the INTCON2 register.
See Section 11.0 “Timer0 Module” for further details
on the Timer0 module.
9.11
An input change on PORTB<7:4> sets flag bit, RBIF of
the INTCON register. The interrupt can be enabled/
disabled by setting/clearing enable bit, RBIE of the
INTCON register. Pins must also be individually
enabled with the IOCB register. Interrupt priority for
PORTB interrupt-on-change is determined by the value
contained in the interrupt priority bit, RBIP of the
INTCON2 register.
9.12
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 5.3
“Data Memory Organization”), the user may need to
save the WREG, STATUS and BSR registers on entry
to the Interrupt Service Routine. Depending on the
user’s application, other registers may also need to be
saved. Example 9-1 saves and restores the WREG,
STATUS and BSR registers during an Interrupt Service
Routine.
PIC18F2XK20/4XK20
TMR0 Interrupt
PORTB Interrupt-on-Change
Context Saving During Interrupts
DS41303B-page 115