PIC16CE624T-04SS View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC16CE624T-04SS

OTP 8-Bit CMOS MCU with EEPROM Data Memory

Microchip Technology 

PIC16CE62X

7.3.1 SWITCHING PRESCALER ASSIGNMENT

The prescaler assignment is fully under software

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

program execution). To avoid an unintended device

RESET, the following instruction sequence

(Example 7-1) must be executed when changing the

prescaler assignment from Timer0 to WDT.

EXAMPLE 7-1: CHANGING PRESCALER

(TIMER0→WDT)

1.BCF STATUS, RP0 ;Skip if already in

; Bank 0

2.CLRWDT

;Clear WDT

3.CLRF TMR0

;Clear TMR0 & Prescaler

4.BSF STATUS, RP0 ;Bank 1

5.MOVLW '00101111’b ;These 3 lines (5, 6, 7)

6.MOVWF OPTION

; are required only if

; desired PS<2:0> are

7.CLRWDT

; 000 or 001

8.MOVLW '00101xxx’b ;Set Postscaler to

9.MOVWF OPTION

; desired WDT rate

10.BCF STATUS, RP0 ;Return to Bank 0

To change prescaler from the WDT to the TMR0

module, use the sequence shown in Example 7-2. This

precaution must be taken even if the WDT is disabled.

EXAMPLE 7-2: CHANGING PRESCALER

(WDT→TIMER0)

CLRWDT

BSF

MOVLW

MOVWF

BCF

STATUS, RP0

b'xxxx0xxx'

OPTION_REG

STATUS, RP0

;Clear WDT and

;prescaler

;Select TMR0, new

;prescale value and

;clock source

TABLE 7-1: REGISTERS ASSOCIATED WITH TIMER0

Address Name

Bit 7

Bit 6 Bit 5 Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Value on:

POR

Value on

All Other

Resets

01h

TMR0 Timer0 module register

xxxx xxxx uuuu uuuu

0Bh/8Bh INTCON GIE PEIE T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000u

81h

OPTION RBPU INTEDG T0CS T0SE PSA

PS2

PS1

PS0 1111 1111 1111 1111

85h

TRISA

—

—

— TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 ---1 1111 ---1 1111

Legend: — = Unimplemented locations, read as ‘0’, x = unknown, u = unchanged.

Note: Shaded bits are not used by TMR0 module.

© 1999 Microchip Technology Inc.

DS40182C-page 39

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