![Microchip Technology PIC12F1501 Скачать руководство пользователя страница 55](http://html1.mh-extra.com/html/microchip-technology/pic12f1501/pic12f1501_manual_1785833055.webp)
PIC16(L)F1508/9
DS40001609E-page 56
2011-2015 Microchip Technology Inc.
5.4.1
TWO-SPEED START-UP MODE
CONFIGURATION
Two-Speed Start-up mode is configured by the following
settings:
• IESO (of the Configuration Words) =
1
;
Internal/External Switchover bit (Two-Speed
Start-up mode enabled).
• SCS (of the OSCCON register) =
00
.
• FOSC<2:0> bits in the Configuration Words
configured for LP, XT or HS mode.
Two-Speed Start-up mode is entered after:
• Power-on Reset (POR) and, if enabled, after
Power-up Timer (PWRT) has expired, or
• Wake-up from Sleep.
5.4.2
TWO-SPEED START-UP
SEQUENCE
1.
Wake-up from Power-on Reset or Sleep.
2.
Instructions begin execution by the internal
oscillator at the frequency set in the IRCF<3:0>
bits of the OSCCON register.
3.
OST enabled to count 1024 clock cycles.
4.
OST timed out, wait for falling edge of the
internal oscillator.
5.
OSTS is set.
6.
System clock held low until the next falling edge
of new clock (LP, XT or HS mode).
7.
System clock is switched to external clock
source.
5.4.3
CHECKING TWO-SPEED CLOCK
STATUS
Checking the state of the OSTS bit of the OSCSTAT
register will confirm if the CPU is running from the
external clock source, as defined by the FOSC<2:0>
bits in the Configuration Words, or the internal oscilla-
tor. See
.
TABLE 5-3:
OSCILLATOR SWITCHING DELAYS
FIGURE 5-8:
TWO-SPEED START-UP
Note:
When FSCM is enabled, Two-Speed
Start-up will automatically be enabled.
Switch From
Switch To
Oscillator Delay
Any clock source
LFINTOSC
1 cycle of each clock source
HFINTOSC
2
s (approx.)
ECH, ECM, ECL, EXTRC
2 cycles
LP, XT, HS
1024 Clock Cycles (OST)
Secondary Oscillator
1024 Secondary Oscillator Cycles
0
1
1022 1023
PC + 1
T
OST
T
INTOSC
OSC1
OSC2
Program Counter
System Clock
PC - N
PC
Содержание PIC12F1501
Страница 307: ...PIC16 L F1508 9 DS40001609E page 308 2011 2015 Microchip Technology Inc NOTES...
Страница 392: ...2011 2015 Microchip Technology Inc DS40001609E page 393 PIC16 L F1508 9 1RWH 6 7 7 588 8 7...
Страница 399: ...PIC16 L F1508 9 DS40001609E page 400 2011 2015 Microchip Technology Inc NOTES...