PIC16F882-E/SPSQTP 查看數據表（PDF） - Microchip Technology

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PIC16F882-E/SPSQTP

28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers

Microchip Technology 

PIC16F882/883/884/886/887

4.7.2

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<2:0>

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.

FIGURE 4-7:

TWO-SPEED START-UP

HFINTOSC

TOST

OSC1 0 1 1022 1023

OSC2

Program Counter PC - N

PC

System Clock

4.7.3

CHECKING TWO-SPEED CLOCK

STATUS

Checking the state of the OSTS bit of the OSCCON

register will confirm if the microcontroller is running

from the external clock source, as defined by the

FOSC<2:0> bits in the Configuration Word Register 1

(CONFIG1), or the internal oscillator.

PC + 1

DS41291G-page 74

 2006-2012 Microchip Technology Inc.

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