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PIC18F8722 FAMILY
DS39646C-page 56 © 2008 Microchip Technology Inc.
4.6 Reset State of Registers
Most registers are unaffected by a Reset. Their status
is unknown on POR and unchanged by all other
Resets. All other registers are forced to a “Reset state”
depending on the type of Reset that occurred.
Most registers are not affected by a WDT wake-up,
since this is viewed as the resumption of normal oper-
ation. Status bits from the RCON register, RI
, TO, PD,
POR
and BOR, are set or cleared differently in different
Reset situations, as indicated in Table 4-3. These bits
are used in software to determine the nature of the
Reset.
Table 4-4 describes the Reset states for all of the
Special Function Registers. These are categorized by
Power-on and Brown-out Resets, Master Clear and
WDT Resets and WDT wake-ups.
TABLE 4-3: STATUS BITS, THEIR SIGNIFICANCE AND THE INITIALIZATION CONDITION
FOR RCON REGISTER
Condition
Program
Counter
RCON Register STKPTR Register
SBOREN RI TO PD POR BOR STKFUL STKUNF
Power-on Reset 0000h 1 11100 0 0
RESET Instruction 0000h u
(2)
0uuuu u u
Brown-out Reset 0000h u
(2)
111u0 u u
MCLR
during Power-Managed
Run Modes
0000h u
(2)
u1uuu u u
MCLR during Power-Managed
Idle Modes and Sleep Mode
0000h u
(2)
u10uu u u
WDT Time-out during Full Power
or Power-Managed Run Mode
0000h u
(2)
u0uuu u u
MCLR during Full Power
Execution
0000h u
(2)
uuuuu u u
Stack Full Reset (STVREN = 1) 0000h u
(2)
uuuuu 1 u
Stack Underflow Reset
(STVREN = 1)
0000h u
(2)
uuuuu u 1
Stack Underflow Error (not an
actual Reset, STVREN = 0)
0000h u
(2)
uuuuu u 1
WDT Time-out during
Power-Managed Idle or
Sleep Modes
PC + 2 u
(2)
u00uu u u
Interrupt Exit from
Power-Managed Modes
PC + 2
(1)
u
(2)
uu0uu u u
Legend: u = unchanged
Note 1: When the wake-up is due to an interrupt and the GIEH or GIEL bits are set, the PC is loaded with the
interrupt vector (008h or 0018h).
2: Reset state is ‘1’ for POR and unchanged for all other Resets when software BOR is enabled
(BOREN<1:0> Configuration bits = 01 and SBOREN = 1). Otherwise, the Reset state is ‘0’.