
2005 Microchip Technology Inc.
Preliminary
DS41265A-page 209
PIC16F946
Even if the flag bits were checked before executing a
SLEEP
instruction, it may be possible for flag bits to
become set before the SLEEP instruction completes. To
determine whether a SLEEP instruction executed, test
the PD bit. If the PD bit is set, the SLEEP instruction
was executed as a NOP.
To ensure that the WDT is cleared, a CLRWDT instruction
should be executed before a SLEEP instruction.
FIGURE 16-10:
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(1)
CLKO(4)
INT pin
INTF flag
(INTCON<1>)
GIE bit
(INTCON<7>)
Instruction Flow
PC
Instruction
Fetched
Instruction
Executed
PC
PC + 1
PC + 2
Inst(PC) = Sleep
Inst(PC - 1)
Inst(PC + 1)
Sleep
Processor in
Sleep
Interrupt Latency(3)
Inst(PC + 2)
Inst(PC + 1)
Inst(0004h)
Inst(0005h)
Inst(0004h)
Dummy Cycle
PC + 2
0004h
0005h
Dummy Cycle
TOST(2)
PC + 2
Note
1:
XT, HS or LP Oscillator mode assumed.
2:
TOST = 1024 TOSC (drawing not to scale). This delay does not apply to EC and RC Oscillator modes.
3:
GIE = 1 assumed. In this case after wake-up, the processor jumps to 0004h. If GIE = 0, execution will continue in-line.
4:
CLKO is not available in XT, HS, LP or EC Oscillator modes, but shown here for timing reference.