PIC16F7X7
The peripheral interrupt flags are contained in the
Special Function Register, PIR1. The corresponding
interrupt enable bits are contained in Special Function
Register, PIE1 and the peripheral interrupt enable bit is
contained in Special Function Register, INTCON.
15.15 Interrupts
The PIC16F7X7 has up to 17 sources of interrupt. The
Interrupt Control register (INTCON) records individual
interrupt requests in flag bits. It also has individual and
global interrupt enable bits.
When an interrupt is serviced, the GIE bit is cleared to
disable any further interrupt, the return address is
pushed onto the stack and the PC is loaded with 0004h.
Once in the Interrupt Service Routine, the source(s) of
the interrupt can be determined by polling the interrupt
flag bits. The interrupt flag bit(s) must be cleared in
software before re-enabling interrupts to avoid
recursive interrupts.
Note:
Individual interrupt flag bits are set regard-
less of the status of their corresponding
mask bit or the GIE bit.
A Global Interrupt Enable bit, GIE (INTCON<7>),
enables (if set) all unmasked interrupts or disables (if
cleared) all interrupts. When bit GIE is enabled and an
interrupt’s flag bit and mask bit are set, the interrupt will
vector immediately. Individual interrupts can be
disabled through their corresponding enable bits in
various registers. Individual interrupt bits are set
regardless of the status of the GIE bit. The GIE bit is
cleared on Reset.
For external interrupt events, such as the INT pin or
PORTB change interrupt, the interrupt latency will be
three or four instruction cycles. The exact latency
depends on when the interrupt event occurs relative to
the current Q cycle. The latency is the same for one or
two-cycle instructions. Individual interrupt flag bits are
set regardless of the status of their corresponding
mask bit, PEIE bit or the GIE bit.
The “return from interrupt” instruction, RETFIE, exits
the interrupt routine as well as sets the GIE bit which
re-enables interrupts.
The RB0/INT pin interrupt, the RB port change interrupt
and the TMR0 overflow interrupt flags are contained in
the INTCON register.
FIGURE 15-11:
INTERRUPT LOGIC
PSPIF(1)
PSPIE(1)
OSFIF
OSFIE
BCLIF
BCLIE
ADIF
ADIE
Wake-up (If in Sleep mode)
TMR0IF
TMR0IE
RCIF
RCIE
INT0IF
INT0IE
TXIF
TXIE
Interrupt to CPU
RBIF
RBIE
SSPIF
SSPIE
PEIE
GIE
CCP1IF
CCP1IE
CCP2IF
CCP2IE
CCP3IF
CCP3IE
TMR2IF
TMR2IE
TMR1IF
TMR1IE
CMIF
CMIE
Note 1: PSP interrupt is implemented only on PIC16F747/777 devices.
DS30498C-page 184
2004 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
