10F222 datasheet(36/86 Pages) MICROCHIP

36 / 86 page

PIC10F220/222

DS41270E-page 34

8.2

Oscillator Configurations

8.2.1

OSCILLATOR TYPES

The PIC10F220/222 devices are offered with internal

oscillator mode only.

• INTOSC: Internal 4/8 MHz Oscillator

8.2.2

INTERNAL 4/8 MHz OSCILLATOR

The internal oscillator provides a 4/8 MHz (nominal)

system clock (see Section 10.0 “Electrical Charac-

teristics” for information on variation over voltage and

temperature).

In addition, a calibration instruction is programmed into

the last address of memory, which contains the calibra-

tion value for the internal oscillator. This location is

always uncode protected, regardless of the code-pro-

tect settings. This value is programmed as a MOVLW XX

instruction where XX is the calibration value and is

placed at the Reset vector. This will load the W register

with the calibration value upon Reset and the PC will

then roll over to the users program at address 0x000.

The user then has the option of writing the value to the

OSCCAL Register (05h) or ignoring it.

OSCCAL, when written to with the calibration value, will

“trim” the internal oscillator to remove process variation

from the oscillator frequency.

8.3

Reset

The device differentiates between various kinds of

Reset:

• Power-on Reset (POR)

•MCLR Reset during normal operation

•MCLR Reset during Sleep

• WDT Time-out Reset during normal operation

• WDT Time-out Reset during Sleep

• Wake-up from Sleep on pin change

Some registers are not reset in any way, they are

unknown on POR and unchanged in any other Reset.

Most other registers are reset to “Reset state” on

Power-on Reset (POR), MCLR, WDT or Wake-up on

pin change Reset during normal operation. They are

not affected by a WDT Reset during Sleep or MCLR

Reset during Sleep, since these Resets are viewed as

resumption of normal operation. The exceptions to this

are TO, PD and GPWUF bits. They are set or cleared

differently in different Reset situations. These bits are

used in software to determine the nature of Reset. See

Table 8-1 for a full description of Reset states of all

registers.

TABLE 8-1:

RESET CONDITIONS FOR REGISTERS – PIC10F220/222

Note:

Erasing the device will also erase the pre-

programmed internal calibration value for

the internal oscillator. The calibration

value must be read prior to erasing the

part so it can be reprogrammed correctly

later.

Address

Power-on Reset

MCLR Reset, WDT Time-out, Wake-up On Pin Change,

W—

qqqq qqqu

(1)

qqqq qqqu

(1)

INDF

00h

xxxx xxxx

uuuu uuuu

TMR0

01h

xxxx xxxx

uuuu uuuu

02h

1111 1111

STATUS

03h

0--1 1xxx

q00q quuu

FSR

04h

111x xxxx

111u uuuu

OSCCAL

05h

1111 1110

uuuu uuuu

GPIO

06h

---- xxxx

---- uuuu

ADCON0

07h

11-- 1100

ADRES

08h

xxxx xxxx

uuuu uuuu

OPTION

—

1111 1111

TRIS

—

---- 1111

Legend:

= unchanged, x = unknown, – = unimplemented bit, read as ‘0’, q = value depends on condition.

Note

Bits <7:2> of W register contain oscillator calibration values due to MOVLW XX instruction at top of memory.

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