PIC12F635/PIC16F636/639
12.1 Configuration Bits
12.0 SPECIAL FEATURES OF THE
CPU
The Configuration Word bits can be programmed (read
as ‘0’), or left unprogrammed (read as ‘1’) to select
The PIC12F635/PIC16F636/639 has a host of features
intended to maximize system reliability, minimize cost
through elimination of external components, provide
power saving features and offer code protection.
various device configurations as shown in Register 12-1.
These bits are mapped in program memory location
2007h.
These features are:
Note:
Address 2007h is beyond the user program
memory space. It belongs to the special
configuration memory space (2000h-
3FFFh), which can be accessed only during
programming. See “PIC12F6XX/16F6XX
Memory Programming Specification”
(DS41204) for more information.
• Reset
- Power-on Reset (POR)
- Wake-up Reset (WUR)
- Power-up Timer (PWRT)
- Oscillator Start-up Timer (OST)
- Brown-out Reset (BOR)
• Interrupts
• Watchdog Timer (WDT)
• Oscillator selection
• Sleep
• Code protection
• ID Locations
• In-Circuit Serial Programming™
The PIC12F635/PIC16F636/639 has two timers that
offer necessary delays on power-up. One is the
Oscillator Start-up Timer (OST), intended to keep the
chip in Reset until the crystal oscillator is stable. The
other is the Power-up Timer (PWRT), which provides a
fixed delay of 64 ms (nominal) on power-up only,
designed to keep the part in Reset while the power
supply stabilizes. There is also circuitry to reset the
device if a brown-out occurs, which can use the
Power-up Timer to provide at least a nominal 64 ms
Reset. With these three functions 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
• Watchdog Timer Wake-up
• An Interrupt
Several oscillator options are also made available to
allow the part to fit the application. The INTOSC option
saves system cost while the LP crystal option saves
power. A set of Configuration bits are used to select
various options (see Register 12-1).
© 2007 Microchip Technology Inc.
DS41232D-page 129
MICROCHIP [ MICROCHIP ]
