CF745 Ver la hoja de datos (PDF) - Microchip Technology

Número de pieza

componentes Descripción

Fabricante

CF745

EPROM/ROM-Based 8-Bit CMOS Microcontroller Series

Microchip Technology 

PIC16C5X

7.0 SPECIAL FEATURES OF THE

CPU

What sets a microcontroller apart from other

processors are special circuits that deal with the

needs of real-time applications. The PIC16C5X family

of microcontrollers has a host of such features

intended to maximize system reliability, minimize cost

through elimination of external components, provide

power saving operating modes and offer code

protection. These features are:

• Oscillator selection

• Reset

• Power-On Reset (POR)

• Device Reset Timer (DRT)

• Watchdog Timer (WDT)

(not implemented on PIC16C52)

• SLEEP

• Code protection

• ID locations (not implemented on PIC16C52)

The PIC16C5X Family has a Watchdog Timer which

can be shut off only through configuration bit WDTE. It

runs off of its own RC oscillator for added reliability.

There is an 18 ms delay provided by the Device Reset

Timer (DRT), intended to keep the chip in reset until

the crystal oscillator is stable. With this timer on-chip,

most applications need no external reset circuitry.

The SLEEP mode is designed to offer a very low

current power-down mode. The user can wake up from

SLEEP through external reset or through a Watchdog

Timer time-out. Several oscillator options are also

made available to allow the part to fit the application.

The RC oscillator option saves system cost while the

LP crystal option saves power. A set of configuration

bits are used to select various options.

7.1 Configuration Bits

Configuration bits can be programmed to select

various device configurations. Two bits are for the

selection of the oscillator type and one bit is the

Watchdog Timer enable bit. Nine bits are code

protection bits (Figure 7-1 and Figure 7-2) for the

PIC16C54, PIC16CR54, PIC16C56, PIC16CR56,

PIC16C58, and PIC16CR58 devices.

QTP or ROM devices have the oscillator configuration

programmed at the factory and these parts are tested

accordingly (see "Product Identification System"

diagrams in the back of this data sheet).

FIGURE 7-1:

CONFIGURATION WORD FOR

PIC16CR54A/C54B/CR54B/C54C/CR54C/C55A/C56A/CR56A/C57C/

CR57B/CR57C/C58B/CR58A/CR58B

CP CP CP CP CP CP CP CP CP WDTE FOSC1 FOSC0 Register: CONFIG

bit11 10

9

8

7

6

5

4

3

2

1

bit0 Address(1): FFFh

bit 11-3: CP: Code protection bits

1 = Code protection off

0 = Code protection on

bit 2:

WDTE: Watchdog timer enable bit

1 = WDT enabled

0 = WDT disabled

bit 1-0:

FOSC1:FOSC0: Oscillator selection bits

11 = RC oscillator

10 = HS oscillator

01 = XT oscillator

00 = LP oscillator

Note 1: Refer to the PIC16C5X Programming Specification (Literature Number DS30190) to deter-

mine how to access the configuration word.

© 1998 Microchip Technology Inc.

Preliminary

DS30453B-page 31

Share Link: