Datasheet

ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller PDIP 18 8-Bit 4 MHz I/O number 12

PIC16HV540

DS40197B-page 14 Preliminary  2000 Microchip Technology Inc.

4.4 OPTION Register

The OPTION register is a 6-bit wide, write-only register

which contains various control bits to configure the

Timer0/WDT prescaler and Timer0.

By executing the OPTION instruction, the contents of

the W register will be transferred to the OPTION regis-

ter. A RESET sets the OPTION<5:0> bits.

Example 4-1 illustrates how to initialize the OPTION

EXAMPLE 4-1: INSTRUCTIONS FOR INITIALIZING OPTION REGISTER

movlw ‘0000 0111’b ; load OPTION setup value into W

OPTION ; initialize OPTION register

U-0 U-0 W-1 W-1 W-1 W-1 W-1 W-1

— — T0CS T0SE PSA PS2 PS1 PS0 W = Writable bit

U = Unimplemented bit

- n = Value at POR reset

bit7 0

bit 7-6: Unimplemented

bit 5: T0CS: Timer0 Clock Source Select bit

1 = Transition on T0CKI pin

0 = Internal instruction cycle clock (CLKOUT)

bit 4: T0SE: Timer0 Source Edge Select bit

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

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

bit 3: PSA: Prescaler Assignment bit

1 = Prescaler assigned to the WDT

0 = Prescaler assigned to Timer0

bit 2-0: PS<2:0>: 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