PIC18F2480 MICROCHIP [Microchip Technology], PIC18F2480 Datasheet - Page 130

• Manufacturer Part Number: PIC18F2480
• Description: 28/40/44-Pin Enhanced Flash Microcontrollers with ECAN Technology, 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18F2480/2580/4480/4580
9.6
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 clear-
ing the corresponding enable bit INTxE. Flag bit INTxF
must be cleared in software in the Interrupt Service
Routine before re-enabling the interrupt.
All external interrupts (INT0, INT1 and INT2) can wake-
up the processor from the power managed modes, if bit
INTxE was set prior to going into power managed
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
(INTCON3<6>) and INT2IP (INTCON3<7>). There is
no priority bit associated with INT0. It is always a high
priority interrupt source.
EXAMPLE 9-1:
DS39637A-page 128
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
Preliminary
; W_TEMP is in virtual bank
; STATUS_TEMP located anywhere
; BSR_TMEP located anywhere
; Restore BSR
; Restore WREG
; Restore STATUS
9.7
In 8-bit mode (which is the default), an overflow in the
TMR0 register (FFh
16-bit mode, an overflow in the TMR0H:TMR0L regis-
ter pair (FFFFh
can be enabled/disabled by setting/clearing enable bit
TMR0IE (INTCON<5>). Interrupt priority for Timer0 is
determined by the value contained in the interrupt
priority bit, TMR0IP (INTCON2<2>). See Section 13.0
“Timer2 Module” for further details on the Timer0
module.
9.8
An input change on PORTB<7:4> sets flag bit, RBIF
(INTCON<0>). The interrupt can be enabled/disabled
by setting/clearing enable bit, RBIE (INTCON<3>).
Interrupt priority for PORTB interrupt-on-change is
determined by the value contained in the interrupt
priority bit, RBIP (INTCON2<0>).
9.9
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.
TMR0 Interrupt
PORTB Interrupt-on-Change
Context Saving During Interrupts
0000h) will set TMR0IF. The interrupt
00h) will set flag bit TMR0IF. In
 2004 Microchip Technology Inc.