PIC16F630/676
9.4.1
RA2/INT INTERRUPT
9.4.2
TMR0 INTERRUPT
External interrupt on RA2/INT pin is edge-triggered;
either rising if INTEDG bit (OPTION<6>) is set, or
falling, if INTEDG bit is clear. When a valid edge
appears on the RA2/INT pin, the INTF bit
(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. See
Section 9.7 for details on SLEEP and Figure 9-13 for
timing of wake-up from SLEEP through RA2/INT
interrupt.
An overflow (FFh → 00h) in the TMR0 register will
set the T0IF (INTCON<2>) bit. The interrupt can
be enabled/disabled by setting/clearing T0IE
(INTCON<5>) bit. For operation of the Timer0 module,
see Section 4.0.
9.4.3
PORTA INTERRUPT
An input change on PORTA change sets the RAIF
(INTCON<0>) bit. The interrupt can be enabled/
disabled by setting/clearing the RAIE (INTCON<3>)
bit. Plus individual pins can be configured through the
IOCA register.
Note: If a change on the I/O pin should occur
when the read operation is being executed
(start of the Q2 cycle), then the RAIF inter-
rupt flag may not get set.
Note: The ANSEL (91h) and CMCON (19h)
registers must be initialized to configure an
analog channel as a digital input. Pins
configured as analog inputs will read ‘0’.
The ANSEL register is defined for the
PIC16F676.
9.4.4
COMPARATOR INTERRUPT
See Section 6.9 for description of comparator interrupt.
9.4.5
A/D CONVERTER INTERRUPT
After a conversion is complete, the ADIF flag (PIR<6>)
is set. The interrupt can be enabled/disabled by setting
or clearing ADIE (PIE<6>).
See Section 7.0 for operation of the A/D converter
interrupt.
FIGURE 9-11:
INT PIN INTERRUPT TIMING
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
OSC1
CLKOUT
3
4
INT pin
1
1
Interrupt Latency
INTF Flag
(INTCON<1>)
5
2
GIE bit
(INTCON<7>)
INSTRUCTION FLOW
PC
PC+1
—
0004h
0005h
PC
PC+1
Instruction
Fetched
Inst (PC+1)
Inst (0004h)
Inst (PC)
Inst (0005h)
Inst (0004h)
Instruction
Executed
Dummy Cycle
Dummy Cycle
Inst (PC)
Inst (PC-1)
Note 1: INTF flag is sampled here (every Q1).
2: Asynchronous interrupt latency = 3-4 TCY. Synchronous latency = 3 TCY, where TCY = instruction cycle time. Latency
is the same whether Inst (PC) is a single cycle or a 2-cycle instruction.
3: CLKOUT is available only in RC Oscillator mode.
4: For minimum width of INT pulse, refer to AC specs.
5: INTF is enabled to be set any time during the Q4-Q1 cycles.
© 2007 Microchip Technology Inc.
DS40039E-page 65
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