PIC10F220IP(2006) View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC10F220IP
(Rev.:2006)

6-Pin, 8-Bit Flash Microcontrollers

Microchip Technology 

PIC10F220/222

6.2.1

SWITCHING PRESCALER

ASSIGNMENT

The prescaler assignment is fully under software

control (i.e., it can be changed “on-the-fly” during pro-

gram execution). To avoid an unintended device Reset,

the following instruction sequence (Example 6-1) must

be executed when changing the prescaler assignment

from Timer0 to the WDT.

EXAMPLE 6-1:

CHANGING PRESCALER

(TIMER0 → WDT)

CLRWDT

;Clear WDT

CLRF TMR0

;Clear TMR0 & Prescaler

MOVLW ‘00xx1111’b ;These 3 lines (5, 6, 7)

OPTION

;are required only if

;desired

CLRWDT

;PS<2:0> are 000 or 001

MOVLW ‘00xx1xxx’b ;Set Postscaler to

OPTION

;desired WDT rate

To change prescaler from the WDT to the Timer0

module, use the sequence shown in Example 6-2. This

sequence must be used even if the WDT is disabled. A

CLRWDT instruction should be executed before

switching the prescaler.

EXAMPLE 6-2:

CHANGING PRESCALER

(WDT→TIMER0)

CLRWDT

MOVLW ‘xxxx0xxx’

OPTION

;Clear WDT and

;prescaler

;Select TMR0, new

;prescale value and

;clock source

FIGURE 6-5:

BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER

TCY (= FOSC/4)

GP2/T0CKI(2)

Pin

0

M

U

1X

1

M

U

0X

Sync

2

Cycles

T0SE(1)

T0CS(1)

PSA(1)

Data Bus

8

TMR0 Reg

Watchdog

Timer

WDT Enable bit

0

M

U

1X

PSA(1)

8-bit Prescaler

8

8-to-1 MUX

PS<2:0>(1)

0

1

MUX

PSA(1)

WDT

Time-Out

Note 1: T0CS, T0SE, PSA, PS<2:0> are bits in the OPTION register.

2: T0CKI is shared with pin GP2 on the PIC10F220/222.

DS41270B-page 28

Preliminary

© 2006 Microchip Technology Inc.

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