Datasheet

PIC10F220/222
DS41270E-page 34 © 2007 Microchip Technology Inc.
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.
Register 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
PC 02h 1111 1111 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 11-- 1100
ADRES 08h xxxx xxxx uuuu uuuu
OPTION — 1111 1111 1111 1111
TRIS — ---- 1111 ---- 1111
Legend: u = unchanged, x = unknown, – = unimplemented bit, read as ‘0’, q = value depends on condition.
Note 1: Bits <7:2> of W register contain oscillator calibration values due to MOVLW XX instruction at top of memory.