PIC16F721-ESS View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC16F721-ESS

20-Pin Flash Microcontrollers

Microchip Technology 

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

Clock from

Ext. System

I/O

CLKIN

PIC® MCU

CLKOUT

PIC16(L)F720/721

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.

TABLE 7-2: SUMMARY OF CONFIGURATION WORD WITH CLOCK SOURCES

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

13:8 —

CONFIG1

7:0 —

—

—

PLLEN

—

— BOREN1 BOREN0

72

CP

MCLRE PWRTE WDTEN

—

FOSC1 FOSC0

13:8 —

—

—

—

—

—

—

—

CONFIG2

73

7:0 —

—

—

—

—

—

WRT1 WRT0

Legend: — = unimplemented location, read as ‘0’. Shaded cells are not used by clock sources.

 2010-2013 Microchip Technology Inc.

DS41430D-page 69

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