PIC18F010T-I/SN データシートの表示（PDF） - Microchip Technology
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PIC18F010T-I/SN Datasheet PDF : 176 Pages
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PIC18F010/020
3.5 Time-out Sequence
On power-up, the time-out sequence is as follows: first,
PWRT time-out is invoked after the POR time delay has
expired; then, OST is activated. The total time-out will
vary based on oscillator configuration and the status of
the PWRT. For example, in Internal Oscillator mode
with the PWRT disabled, there will be no time-out at all.
Figure 3-3, Figure 3-4, Figure 3-5 and Figure 3-6
depict time-out sequences on power-up.
Since the time-outs occur from the POR pulse, if MCLR
is kept low long enough, the time-outs will expire.
Bringing MCLR high will begin execution immediately
(Figure 3-5). This is useful for testing purposes or to
synchronize more than one PIC18F010/020 device
operating in parallel.
Table 3-2 shows the RESET conditions for some
Special Function Registers, while Table 3-3 shows the
RESET conditions for all the registers.
TABLE 3-1: TIME-OUT IN VARIOUS SITUATIONS
Oscillator
Configuration
Power-up(1)
PWRTE = 0
PWRTE = 1
HS, XT, LP
72 ms + 1024Tosc
1024Tosc
EC
72 ms
—
External Oscillator
72 ms
—
Internal Oscillator(2)
72 ms
—
Note 1: 72 ms is the nominal power-up timer delay.
2: 8-cycle delay.
Brown-out(1)
72 ms + 1024Tosc
72 ms
72 ms
72 ms
Wake-up from
SLEEP or
Oscillator Switch
1024Tosc
—
—
—
REGISTER 3-1: RCON REGISTER BITS AND POSITIONS
R/W-0
U-0
IPEN
—
bit 7
U-0
R/W-1
R-1
—
RI
TO
R-1
R/W-1 R/W-1
PD
POR
BOR
bit 0
TABLE 3-2: STATUS BITS, THEIR SIGNIFICANCE AND THE INITIALIZATION CONDITION FOR
RCON REGISTER
Condition
Program
Counter
RCON
Register
RI TO PD
Power-on Reset
0000h
00-1 1100 1 1 1
MCLR Reset during normal
operation
0000h
00-u uuuu u u u
Software Reset during normal 0000h
operation
0u-0 uuuu 0 u u
Stack Full Reset during normal 0000h
operation
0u-u uu11 u u u
Stack Underflow Reset during 0000h
normal operation
0u-u uu11 u u u
MCLR Reset during SLEEP
0000h
00-u 10uu u 1 0
WDT Reset
0000h
0u-u 01uu 1 0 1
WDT Wake-up
PC + 2 uu-u 00uu u 0 0
Brown-out Reset
0000h
0u-1 11u0 1 1 1
Interrupt Wake-up from SLEEP PC + 2(1) uu-u 00uu u 1 0
Legend: u = unchanged, x = unknown, - = unimplemented bit, read as '0'.
POR
0
u
u
u
u
u
u
u
1
u
BOR
0
u
u
u
u
u
u
u
0
u
STKFUL
u
u
u
1
u
u
u
u
u
u
STKUNF
u
u
u
u
1
u
u
u
u
u
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 (0x000008h or 0x000018h).
2001 Microchip Technology Inc.
Preliminary
DS41142A-page 17
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