Datasheet
2000 Microchip Technology Inc. Preliminary DS40197B-page 31
PIC16HV540
7.0 SPECIAL FEATURES OF THE
CPU
What sets a microcontroller apart from other proces-
sors are special circuits that deal with the needs of real-
time applications. The PIC16HV540 family of micro-
controllers has a host of such features intended to max-
imize system reliability, minimize cost through
elimination of external components, provide power sav-
ing operating modes and offer code protection. These
features are:
• Oscillator selection
• Reset
• Power-On Reset (POR)
• Brown-out Detect
• Device Reset Timer (DRT)
• Wake-up from SLEEP on Pin Change
• Enhanced Watchdog Timer (WDT)
• SLEEP
• Code protection
The PIC16HV540 Family has a Watchdog Timer which
can be shut off only through configuration bit WDTEN.
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 cur-
rent 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) for the PIC16HV540 devices.
REGISTER 7-1: CONFIGURATION WORD FOR PIC16HV540
CP CP CP CP CP CP CP CP CP WDTEN FOSC1FOSC0 Register:CONFIG
Address
(1)
:0FFFh
bit11 bit0
bit 11-3: CP: Code Protection bits
1 = Code protection off
0 = Code protection on
bit 2: WDTEN: Watchdog Timer Enable bit
1 = WDT enabled
0 = WDT disabled (control is placed on the SWDTEN
bit)
bit 1-0: F
OSC<1:0>: 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 determine how to
access the configuration word.