PIC12F629/675
The first event will cause a device Reset. The two latter
events are considered a continuation of program exe-
cution. The TO and PD bits in the STATUS register can
be used to determine the cause of device Reset. The
PD bit, which is set on power-up, is cleared when Sleep
is invoked. TO bit is cleared if WDT Wake-up occurred.
9.7
Power-Down Mode (Sleep)
The Power-down mode is entered by executing a
SLEEPinstruction.
If the Watchdog Timer is enabled:
• WDT will be cleared but keeps running
• PD bit in the STATUS register is cleared
• TO bit is set
When the SLEEP instruction is being executed, the
next instruction (PC + 1) is pre-fetched. For the device
to wake-up through an interrupt event, the correspond-
ing interrupt enable bit must be set (enabled). Wake-up
is regardless of the state of the GIE bit. If the GIE bit is
clear (disabled), the device continues execution at the
instruction after the SLEEPinstruction. If the GIE bit is
set (enabled), the device executes the instruction after
the SLEEPinstruction, then branches to the interrupt
address (0004h). In cases where the execution of the
instruction following SLEEP is not desirable, the user
should have an NOPafter the SLEEPinstruction.
• Oscillator driver is turned off
• I/O ports maintain the status they had before
Sleep was executed (driving high, low, or
high-impedance).
For lowest current consumption in this mode, all I/O
pins should be either at VDD, or VSS, with no external
circuitry drawing current from the I/O pin and the com-
parators and CVREF should be disabled. I/O pins that
are high-impedance inputs should be pulled high or low
externally to avoid switching currents caused by float-
ing inputs. The T0CKI input should also be at VDD or
VSS for lowest current consumption. The contribution
from on-chip pull-ups on GPIO should be considered.
Note: If the global interrupts are disabled (GIE is
cleared), but any interrupt source has both
its interrupt enable bit and the correspond-
ing interrupt flag bits set, the device will
immediately wake-up from Sleep. The
SLEEPinstruction is completely executed.
The MCLR pin must be at a logic high level (VIHMC).
Note: It should be noted that a Reset generated
by a WDT Time-out does not drive MCLR
pin low.
The WDT is cleared when the device wakes up from
Sleep, regardless of the source of wake-up.
9.7.1
WAKE-UP FROM SLEEP
The device can wake-up from Sleep through one of the
following events:
1. External Reset input on MCLR pin
2. Watchdog Timer Wake-up (if WDT was enabled)
3. Interrupt from GP2/INT pin, GPIO change, or a
peripheral interrupt.
FIGURE 9-13:
WAKE-UP FROM SLEEP THROUGH INTERRUPT
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
OSC1
CLKOUT(4)
INT pin
(2)
TOST
INTF flag
(INTCON<1>)
Interrupt Latency
(Note 2)
GIE bit
(INTCON<7>)
Processor in
Sleep
INSTRUCTION FLOW
PC
PC
PC + 1
PC + 2
PC + 2
PC + 2
0004h
0005h
Instruction
Inst(0004h)
Inst(PC + 1)
Inst(PC + 2)
Inst(0005h)
Inst(PC) = Sleep
Inst(PC - 1)
Fetched
Instruction
Executed
Dummy cycle
Dummy cycle
Sleep
Inst(PC + 1)
Inst(0004h)
Note 1: XT, HS or LP Oscillator mode assumed.
2: TOST = 1024TOSC (drawing not to scale). Approximately 1 s delay will be there for RC Osc mode. See Section 12 for wake-up from
Sleep delay in INTOSC mode.
3: GIE = 1assumed. In this case after wake-up, the processor jumps to the interrupt routine. If GIE = 0, execution will continue in-line.
4: CLKOUT is not available in XT, HS, LP or EC Osc modes, but shown here for timing reference.
DS41190G-page 68
2010 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
