PIC12F508 datasheet(41/98 Pages) MICROCHIP

41 / 98 page

 2004 Microchip Technology Inc.

Preliminary

DS41236A-page 39

PIC12F508/509/16F505

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

PIC12F508/509/16F505

microcontrollers have 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)

- Wake-up from Sleep on Pin Change

• Watchdog Timer (WDT)

• Sleep

• Code Protection

• ID Locations

• In-Circuit Serial Programming™

•Clock Out

The PIC12F508/509/16F505 devices have a Watchdog

Timer, which can be shut off only through configuration

bit WDTE. It runs off of its own RC oscillator for added

reliability. If using HS (PIC16F505), XT or LP selectable

oscillator options, there is always an 18 ms (nominal)

delay provided by the Device Reset Timer (DRT),

intended to keep the chip in Reset until the crystal

oscillator is stable. If using INTRC or EXTRC, there is

an 18 ms delay only on VDD power-up. 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 a change on input pins or through a Watchdog

Timer time-out. Several oscillator options are also

made available to allow the part to fit the application,

including an internal 4 MHz oscillator. The EXTRC

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

The

PIC12F508/509/16F505

Configuration

Words

consist

bits.

Configuration

bits

can

programmed to select various device configurations.

Three bits are for the selection of the oscillator type;

(two bits on the PIC12F508/509), one bit is the

Watchdog Timer enable bit, one bit is the MCLR enable

bit and one bit is for code protection (Register 7-1,

CONFIGURATION WORD FOR PIC12F508/509(1)

—

MCLRE

WDTE

FOSC1

FOSC0

bit 11

bit 0

bit 11-5

Unimplemented: Read as ‘0’

bit 4

MCLRE: GP3/MCLR Pin Function Select bit

= GP3/MCLR pin function is MCLR

= GP3/MCLR pin function is digital I/O, MCLR internally tied to VDD

bit 3

CP: Code Protection bit

= Code protection off

= Code protection on

bit 2

WDTE: Watchdog Timer Enable bit

= WDT enabled

= WDT disabled

bit 1-0

FOSC<1:0>: Oscillator Selection bits

= EXTRC = external selection bits

= INTRC = internal RC oscillator

= XT oscillator

= LP oscillator

Note 1:

Refer to the “PIC12F508/509 Memory Programming Specifications” (DS41227) to determine how to access

the Configuration Word. The Configuration Word is not user addressable during device operation.

Legend:

R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = bit is set

‘0’ = bit is cleared

x = bit is unknown

PIC12F508 bảng dữ liệu(PDF) 41 Page - Microchip Technology

PIC12F508 bảng dữ liệu(HTML) 41 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98

bảng dữ liệu tải về

Link URL