Datasheet

ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller PDIP 8 8-Bit 4 MHz I/O number 5

 1999 Microchip Technology Inc. DS40139E-page 17

PIC12C5XX

4.4 OPTION Register

The OPTION register is a 8-bit wide, write-only

configure the Timer0/WDT prescaler and Timer0.

By executing the OPTION instruction, the contents of

the W register will be transferred to the OPTION

Note: If TRIS bit is set to ‘0’, the wake-up on

change and pull-up functions are disabled

for that pin; i.e., note that TRIS overrides

OPTION control of GPPU

and GPWU.

Note: If the T0CS bit is set to ‘1’, GP2 is forced to

be an input even if TRIS GP2 = ‘0’.

FIGURE 4-5: OPTION REGISTER

W-1 W-1 W-1 W-1 W-1 W-1 W-1 W-1

GPWU

GPPU T0CS T0SE PSA PS2 PS1 PS0 W = Writable bit

U = Unimplemented bit

- n = Value at POR reset

Reference Table 4-1 for

other resets.

bit7 6 5 4 3 2 1 bit0

bit 7: GPWU

: Enable wake-up on pin change (GP0, GP1, GP3)

1 = Disabled

0 = Enabled

bit 6: GPPU

: Enable weak pull-ups (GP0, GP1, GP3)

1 = Disabled

0 = Enabled

bit 5: T0CS: Timer0 clock source select bit

1 = Transition on T0CKI pin

0 = Transition on internal instruction cycle clock, Fosc/4

bit 4: T0SE: Timer0 source edge select bit

1 = Increment on high to low transition on the T0CKI pin

0 = Increment on low to high transition on the T0CKI pin

bit 3: PSA: Prescaler assignment bit

1 = Prescaler assigned to the WDT

0 = Prescaler assigned to Timer0

bit 2-0: PS2:PS0: Prescaler rate select bits

000

001

010

011

100

101

110

111

1 : 2

1 : 4

1 : 8

1 : 16

1 : 32

1 : 64

1 : 128

1 : 256

1 : 1