PIC16F684-I/SLG Microchip, PIC16F684-I/SLG Datasheet - Page 21

• Manufacturer Part Number: PIC16F684-I/SLG
• Description: pic, flash, Microcontrollers, Microprocessors, Semiconductors and Actives, ic, mcu
• Manufacturer: Microchip

3.0
3.1
The PIC16F684 has a wide variety of clock sources
and selection features to allow it to be used in a wide
range of applications while maximizing performance
and
illustrates a block diagram of the PIC16F684 clock
sources.
Clock sources can be configured from external
oscillators,
resonators and Resistor-Capacitor (RC) circuits. In
addition, the system clock source can be configured
from one of two internal oscillators, with a choice of
speeds selectable via software. Additional clock
features include:
• Selectable system clock source between external
• Two-Speed Clock Start-up mode, which mini-
• Fail-Safe Clock Monitor (FSCM) designed to
FIGURE 3-1:
 2004 Microchip Technology Inc.
or internal via software.
mizes latency between external oscillator start-up
and code execution.
detect a failure of the external clock source (LP,
XT, HS, EC or RC modes) and switch to the
internal oscillator.
OSC2
OSC1
minimizing
CLOCK SOURCES
Overview
quartz
External Oscillator
Internal Oscillator
power
HFINTOSC
LFINTOSC
31 kHz
8 MHz
PIC16F684 CLOCK SOURCE BLOCK DIAGRAM
crystal
consumption.
Sleep
resonators,
Figure 3-1
ceramic
500 kHz
250 kHz
125 kHz
31 kHz
8 MHz
4 MHz
2 MHz
1 MHz
Preliminary
(OSCCON<6:4>)
IRCF<2:0>
111
110
101
100
011
010
001
000
The PIC16F684 can be configured in one of eight clock
modes.
1.
2.
3.
4.
5.
6.
7.
8.
Clock source modes are configured by the FOSC<2:0>
bits
Section 12.0 “Special Features of the CPU”). The
internal clock can be generated by two oscillators. The
HFINTOSC is a high-frequency calibrated oscillator.
The LFINTOSC is a low-frequency uncalibrated
oscillator.
LP, XT, HS, RC, RCIO, EC
EC – External clock with I/O on RA4.
LP – Low gain Crystal or Ceramic Resonator
Oscillator mode.
tor Oscillator mode.
HS – High gain Crystal or Ceramic Resonator
mode.
RC – External Resistor-Capacitor (RC) with
F
RCIO – External Resistor-Capacitor with I/O on
RA4.
INTRC – Internal oscillator with F
on RA4 and I/O on RA5.
INTRCIO – Internal oscillator with I/O on RA4
and RA5.
XT – Medium gain Crystal or Ceramic Resona-
OSC
in
/4 output on RA4.
the
Power-up Timer (PWRT)
Watchdog Timer (WDT)
Fail-Safe Clock Monitor (FSCM)
Configuration
(Configuration Word)
(OSCCON<0>)
FOSC<2:0>
PIC16F684
SCS
Word
(CPU and Peripherals)
DS41202C-page 19
System Clock
OSC
register
/4 output
(see