Datasheet
1996-2013 Microchip Technology Inc. Preliminary DS40143E-page 31
PIC16C55X
6.0 SPECIAL FEATURES OF THE
CPU
What sets a microcontroller apart from other
processors are special circuits to deal with the needs of
real-time applications. The PIC16C55X family 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 are:
1. OSC selection
2. RESET
3. Power-on Reset (POR)
4. Power-up Timer (PWRT)
5. Oscillator Start-Up Timer (OST)
6. Interrupts
7. Watchdog Timer (WDT)
8. SLEEP
9. Code protection
10. ID Locations
11. In-circuit serial programming™
The PIC16C55X has a Watchdog Timer which is
controlled by configuration bits. It runs off its own RC
oscillator for added reliability. There are two timers that
offer necessary delays on power-up. One is the
Oscillator Start-up Timer (OST), which is intended to
keep the chip in RESET until the crystal oscillator is sta-
ble. The other is the Power-up Timer (PWRT), which
provides a fixed delay of 72 ms (nominal) on power-up
only, designed to keep the part in RESET while the
power supply stabilizes. With these two functions on-
chip, most applications need no external RESET cir-
cuitry.
The SLEEP mode is designed to offer a very low
current Power-down mode. The user can wake-up from
SLEEP through external RESET, Watchdog Timer
wake-up or through an interrupt. 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.
6.1 Configuration Bits
The configuration bits can be programmed (read as '0')
or left unprogrammed (read as '1') to select various
device configurations. These bits are mapped in
program memory location 2007h.
The user will note that address 2007h is beyond
the user program memory space. In fact, it belongs
to the special test/configuration memory space
(2000h – 3FFFh), which can be accessed only during
programming.