Datasheet

 2010-2013 Microchip Technology Inc. DS40001430E-page 69
PIC16(L)F720/721
7.6 External Clock Modes
7.6.1 EC MODE
The External Clock (EC) mode allows an externally
generated logic level as the system clock source. When
operating in this mode, an external clock source is
connected to the CLKIN input and the CLKOUT is
available for general purpose I/O. Figure 7-2 shows the
pin connections for EC mode.
FIGURE 7-2: EXTERNAL CLOCK (EC)
MODE OPERATION
TABLE 7-2: SUMMARY OF CONFIGURATION WORD WITH CLOCK SOURCES
CLKIN
CLKOUT
I/O
Clock from
Ext. System
PIC
®
MCU
TABLE 7-1: SUMMARY OF REGISTERS ASSOCIATED WITH CLOCK SOURCES
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Register
on Page
OSCCON
— — IRCF1 IRCF0 ICSL ICSS — — 67
OSCTUNE — — TUN5 TUN4 TUN3 TUN2 TUN1 TUN0 68
Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by
oscillators.
Name Bits Bit -/7 Bit -/6 Bit 13/5 Bit 12/4 Bit 11/3 Bit 10/2 Bit 9/1 Bit 8/0
Register
on Page
CONFIG1
13:8
— — — PLLEN — — BOREN1 BOREN0
72
7:0
— CP MCLRE PWRTE WDTEN —FOSC1FOSC0
CONFIG2
13:8
— — — — — — — —
73
7:0
— — — — — — WRT1 WRT0
Legend: — = unimplemented location, read as ‘0’. Shaded cells are not used by clock sources.