PIC12F683
The PIC12F683 can be configured in one of eight clock
modes.
3.0
3.1
CLOCK SOURCES
Overview
1. EC – External clock with I/O on GP4.
2. LP – Low gain crystal or Ceramic Resonator
Oscillator mode.
The PIC12F683 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 mini-
mizing power consumption. Figure 3-1 illustrates a block
diagram of the PIC12F683 clock sources.
3. XT – Medium gain crystal or Ceramic Resonator
Oscillator mode.
4. HS – High gain crystal or Ceramic Resonator
mode.
Clock sources can be configured from external oscilla-
tors, quartz crystal resonators, ceramic resonators and
Resistor-Capacitor (RC) circuits. In addition, the sys-
tem clock source can be configured from one of two
internal oscillators, with a choice of speeds selectable
via software. Additional clock features include:
5. RC – External Resistor-Capacitor (RC) with
FOSC/4 output on GP4
6. RCIO – External Resistor-Capacitor with I/O on
GP4.
7. INTRC – Internal oscillator with FOSC/4 output
on GP4 and I/O on GP5.
• Selectable system clock source between external
or internal via software.
8. INTRCIO – Internal oscillator with I/O on GP4
and GP5.
• Two-Speed Clock Start-up mode, which
minimizes latency between external oscillator
start-up and code execution.
Clock source modes are configured by the FOSC<2:0>
bits in the Configuration Word register (see
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.
• Fail-Safe Clock Monitor (FSCM) designed to
detect a failure of the external clock source (LP,
XT, HS, EC or RC modes) and switch to the
internal oscillator.
FIGURE 3-1:
PIC12F683 CLOCK SOURCE BLOCK DIAGRAM
FOSC<2:0>
(Configuration Word)
External Oscillator
SCS
(OSCCON<0>)
OSC2
OSC1
Sleep
LP, XT, HS, RC, RCIO, EC
IRCF<2:0>
(OSCCON<6:4>)
System Clock
(CPU and Peripherals)
8 MHz
111
110
101
Internal Oscillator
4 MHz
2 MHz
1 MHz
HFINTOSC
8 MHz
100
011
010
001
000
500 kHz
250 kHz
125 kHz
31 kHz
LFINTOSC
31 kHz
Power-up Timer (PWRT)
Watchdog Timer (WDT)
Fail-Safe Clock Monitor (FSCM)
2004 Microchip Technology Inc.
Preliminary
DS41211B-page 19
MICROCHIP [ MICROCHIP ]
