PIC16F684-I/SLG Microchip, PIC16F684-I/SLG Datasheet - Page 103

• Manufacturer Part Number: PIC16F684-I/SLG
• Description: pic, flash, Microcontrollers, Microprocessors, Semiconductors and Actives, ic, mcu
• Manufacturer: Microchip

12.4
The PIC16F684 has 11 sources of interrupt:
• External Interrupt RA2/INT
• TMR0 Overflow Interrupt
• PORTA Change Interrupts
• 2 Comparator Interrupts
• A/D Interrupt
• Timer1 Overflow Interrupt
• Timer2 Match Interrupt
• EEPROM Data Write Interrupt
• Fail-Safe Clock Monitor Interrupt
• Enhanced CCP Interrupt
The Interrupt Control register (INTCON) and Peripheral
Interrupt Request Register 1 (PIR1) record individual
interrupt requests in flag bits. The INTCON register
also has individual and global interrupt enable bits.
A Global Interrupt Enable bit, GIE (INTCON<7>),
enables (if set) all unmasked interrupts, or disables (if
cleared) all interrupts. Individual interrupts can be
disabled through their corresponding enable bits in the
INTCON register and PIE1 register. GIE is cleared on
Reset.
The Return from Interrupt instruction, RETFIE, exits
the interrupt routine, as well as sets the GIE bit,
which re-enables unmasked interrupts.
The following interrupt flags are contained in the
INTCON register:
• INT Pin Interrupt
• PORTA Change Interrupt
• TMR0 Overflow Interrupt
The peripheral interrupt flags are contained in the
special register, PIR1. The corresponding interrupt
enable bit is contained in special register, PIE1.
The following interrupt flags are contained in the PIR1
register:
• EEPROM Data Write Interrupt
• A/D Interrupt
• 2 Comparator Interrupts
• Timer1 Overflow Interrupt
• Timer2 Match Interrupt
• Fail-Safe Clock Monitor Interrupt
• Enhanced CCP Interrupt
When an interrupt is serviced:
• The GIE is cleared to disable any further interrupt.
• The return address is pushed onto the stack.
• The PC is loaded with 0004h.
 2004 Microchip Technology Inc.
Interrupts
Preliminary
For external interrupt events, such as the INT pin or
PORTA change interrupt, the interrupt latency will be
three or four instruction cycles. The exact latency
depends upon when the interrupt event occurs (see
Figure 12-8). The latency is the same for one or two-
cycle instructions. 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 multiple interrupt
requests.
For
comparators, A/D, data EEPROM or Enhanced CCP
modules, refer to the respective peripheral section.
12.4.1
External interrupt on RA2/INT pin is edge-triggered;
either rising if the INTEDG bit (Option<6>) is set, or
falling, if the INTEDG bit is clear. When a valid edge
appears
(INTCON<1>) is set. This interrupt can be disabled by
clearing the INTE control bit (INTCON<4>). The INTF
bit must be cleared in software in the Interrupt Service
Routine before re-enabling this interrupt. The RA2/INT
interrupt can wake-up the processor from Sleep, if the
INTE bit was set prior to going into Sleep. The status of
the GIE bit decides whether or not the processor
branches to the interrupt vector following wake-up
(0004h). See Section 12.7 “Power-Down Mode
(Sleep)” for details on Sleep and Figure 12-10 for
timing of wake-up from Sleep through RA2/INT
interrupt.
Note:
Note 1: Individual interrupt flag bits are set,
additional
2: When an instruction that clears the GIE
on
RA2/INT INTERRUPT
The ANSEL (91h) and CMCON0 (19h)
registers must be initialized to configure
an analog channel as a digital input. Pins
configured as analog inputs will read ‘0’.
regardless
corresponding mask bit or the GIE bit.
bit is executed, any interrupts that were
pending for execution in the next cycle
are ignored. The interrupts, which were
ignored, are still pending to be serviced
when the GIE bit is set again.
the
information
RA2/INT
of
PIC16F684
the
on
pin,
DS41202C-page 101
status
Timer1,
the
INTF
of
Timer2,
their
bit