PIC16F818/819
FIGURE 12-9:
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
(2)
CLKO(4)
TOST
INT pin
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
Fetched
Inst(0004h)
Inst(PC + 1)
Inst(PC + 2)
Inst(0005h)
Inst(PC) = Sleep
Instruction
Executed
Dummy Cycle
Dummy Cycle
Sleep
Inst(PC + 1)
Inst(PC – 1)
Inst(0004h)
Note 1: XT, HS or LP Oscillator mode assumed.
2: TOST = 1024 TOSC (drawing not to scale). This delay will not be there for RC Oscillator 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: CLKO is not available in these oscillator modes but shown here for timing reference.
12.14 In-Circuit Debugger
12.15 Program Verification/Code
Protection
When the DEBUG bit in the Configuration Word is
programmed to a ‘0’, the In-Circuit Debugger function-
ality is enabled. This function allows simple debugging
functions when used with MPLAB® ICD. When the
microcontroller has this feature enabled, some of the
resources are not available for general use. Table 12-6
shows which features are consumed by the background
debugger.
If the code protection bit(s) have not been
programmed, the on-chip program memory can be
read out for verification purposes.
12.16 ID Locations
Four memory locations (2000h-2003h) are designated
as ID locations, where the user can store checksum or
other code identification numbers. These locations are
not accessible during normal execution but are
readable and writable during program/verify. It is
recommended that only the four Least Significant bits
of the ID location are used.
TABLE 12-6: DEBUGGER RESOURCES
I/O pins
RB6, RB7
1 level
Stack
Program Memory
Address 0000h must be NOP
Last 100h words
Data Memory
0x070 (0x0F0, 0x170, 0x1F0)
0x1EB-0x1EF
To use the In-Circuit Debugger function of the micro-
controller, the design must implement In-Circuit Serial
Programming connections to MCLR/VPP, VDD, GND,
RB7 and RB6. This will interface to the in-circuit
debugger module available from Microchip or one of
the third party development tool companies.
DS39598E-page 100
2004 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
