
PIC16CE62X
DS40182C-page 60
1999 Microchip Technology Inc.
10.5.1
RB0/INT INTERRUPT
External interrupt on RB0/INT pin is edge triggered;
either rising if INTEDG bit (OPTION<6>) is set, or fall-
ing, if INTEDG bit is clear. When a valid edge appears
on the RB0/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 RB0/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
details on SLEEP and Figure 10-19 for timing of
wake-up from SLEEP through RB0/INT interrupt.
10.5.2
TMR0 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,
10.5.3
PORTB INTERRUPT
An input change on PORTB <7:4> sets the RBIF
(INTCON<0>) bit. The interrupt can be enabled/dis-
abled by setting/clearing the RBIE (INTCON<4>) bit.
10.5.4
COMPARATOR INTERRUPT
interrupts.
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 RBIF inter-
rupt flag may not get set.
FIGURE 10-16: INT PIN INTERRUPT TIMING
Q2
Q1
Q3
Q4
Q2
Q1
Q3
Q4
Q2
Q1
Q3
Q4
Q2
Q1
Q3
Q4
Q2
Q1
Q3
Q4
OSC1
CLKOUT
INT pin
INTF flag
(INTCON<1>)
GIE bit
(INTCON<7>)
INSTRUCTION FLOW
PC
Instruction
fetched
Instruction
executed
Interrupt Latency
PC
PC+1
0004h
0005h
Inst (0004h)
Inst (0005h)
Dummy Cycle
Inst (PC)
Inst (PC+1)
Inst (PC-1)
Inst (0004h)
Dummy Cycle
Inst (PC)
—
1
4
5
1
Note 1: INTF flag is sampled here (every Q1).
2: Interrupt latency = 3-4 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 anytime during the Q4-Q1 cycles.
2
3