PIC16C5X
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.
7.0
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
intended to maximize system reliability, minimize cost
through elimination of external components, provide
power saving operating modes and offer code
protection. These features are:
a host of such features
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.
• Oscillator selection
• Reset
• Power-On Reset (POR)
• Device Reset Timer (DRT)
• Watchdog Timer (WDT)
(not implemented on PIC16C52)
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).
• 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.
FIGURE 7-1: CONFIGURATION WORD FOR
PIC16CR54A/C54B/CR54B/C54C/CR54C/C55A/C56A/CR56A/C57C/
CR57B/CR57C/C58B/CR58A/CR58B
CP
CP
10
CP
9
CP
8
CP
7
CP
6
CP
5
CP
4
CP
3
WDTE FOSC1 FOSC0
bit0
Register: CONFIG
(1)
Address
:
FFFh
bit11
2
1
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
MICROCHIP [ MICROCHIP ]
