PIC16F753 datasheet(35/230 Pages) MICROCHIP

35 / 230 page

 2013-2015 Microchip Technology Inc.

DS40001709C-page 35

PIC16F753/HV753

4.2

Clock Source Modes

Clock Source modes can be classified as external or

internal:

• The External Clock mode relies on an external

clock for the clock source. For example, a clock

module or clock output from another circuit.

• Internal clock sources are contained internally

within the oscillator module. The oscillator module

has four selectable clock frequencies:

-8 MHz

-4 MHz

-1 MHz

-31 kHz

The system clock can be selected between external or

internal clock sources via the FOSC0 bit of the

Configuration Word register (CONFIG).

4.2.1

EC MODE

The External Clock (EC) mode allows an externally

generated logic as the system clock source. The EC

clock mode is selected when the FOSC0 bit of the

Configuration Word is set.

When operating in this mode, an external clock source

must be connected to the CLKIN input. The CLKOUT is

available for either general purpose I/O or system clock

output. Figure 4-3 shows the pin connections for EC

mode.

Because the PIC® MCU design is fully static, stopping

the external clock input will have the effect of halting the

device while leaving all data intact. Upon restarting the

external clock, the device will resume operation as if no

time had elapsed.

FIGURE 4-3:

EXTERNAL CLOCK (EC)

MODE OPERATION

4.2.2

INTERNAL CLOCK MODE

Internal Clock mode configures the internal oscillators

as the system clock source. The Internal Clock mode is

selected when the FOSC0 bit of the Configuration

Word is cleared. The source and frequency are

selected with the IRCF<1:0> bits of the OSCCON

When one of the HFINTOSC frequencies is selected,

the frequency of the internal oscillator can be trimmed

by adjusting the TUN<4:0> bits of the OSCTUNE

Operation after a Power-on Reset (POR) or wake-up

from Sleep is delayed by the oscillator start-up time.

Delays are typically longer for the LFINTOSC than

HFINTOSC because of the very low-power operation

and relatively narrow bandwidth of the LF internal

oscillator. However, when another peripheral keeps the

oscillator running during Sleep, the start-up time is

delayed to allow the memory bias to stabilize.

FIGURE 4-4:

INTERNAL CLOCK MODE

OPERATION

4.2.2.1

Oscillator Ready Bits

The HTS and LTS bits of the OSCCON register indicate

the

status

the

HFINTOSC

and

LFINTOSC,

respectively. When either bit is set, it indicates that the

corresponding oscillator is running and stable.

CLKIN

CLKOUT(1)

I/O

Clock from

Ext. System

PIC® MCU

Note

Alternate pin functions are listed in

Section 1.0 “Device Overview”.

CLKOUT(1)

I/O

PIC® MCU

Note

Alternate pin functions are listed in

Section 1.0 “Device Overview”.

I/O

CLKIN(1)

PIC16F753 数据表(PDF) 35 Page - Microchip Technology

PIC16F753 数据表(HTML) 35 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

数据表下载