PIC16C64X Datasheet, PDF (22/136 Pages) Microchip Technology – 8-Bit EPROM Microcontrollers with Analog Comparators

PIC16C64X & PIC16C66X
4.2.2.2 OPTION REGISTER
The OPTION register is a readable and writable
register which contains various control bits to configure
the TMR0/WDT prescaler, the external RB0/INT
interrupt, TMR0, and the weak pull-ups on PORTB.
Note: To achieve a 1:1 prescaler assignment for
TMR0, assign the prescaler to the WDT.
FIGURE 4-6: OPTION REGISTER (ADDRESS 81h)
R/W-1
RBPU
bit7
R/W-1
INTEDG
R/W-1
T0CS
R/W-1 R/W-1
T0SE PSA
R/W-1
PS2
R/W-1 R/W-1
PS1 PS0
bit0
bit 7:
RBPU: PORTB Pull-up Enable bit
1 = PORTB pull-ups are disabled
0 = PORTB pull-ups are enabled by individual port latch values
bit 6:
INTEDG: Interrupt Edge Select bit
1 = Interrupt on rising edge of RB0/INT pin
0 = Interrupt on falling edge of RB0/INT pin
bit 5:
T0CS: TMR0 Clock Source Select bit
1 = Transition on RA4/T0CKI pin
0 = Internal instruction cycle clock (CLKOUT)
bit 4:
T0SE: TMR0 Source Edge Select bit
1 = Increment on high-to-low transition on RA4/T0CKI pin
0 = Increment on low-to-high transition on RA4/T0CKI pin
bit 3:
PSA: Prescaler Assignment bit
1 = Prescaler is assigned to the WDT
0 = Prescaler is assigned to the Timer0 module
bit 2-0: PS2:PS0: Prescaler Rate Select bits
Bit Value TMR0 Rate WDT Rate
000
1:2
1:1
001
1:4
1:2
010
1:8
1:4
011
1 : 16
1:8
100
1 : 32
1 : 16
101
1 : 64
1 : 32
110
1 : 128
1 : 64
111
1 : 256
1 : 128
R= Readable bit
W= Writable bit
U= Unimplemented bit,
read as ‘0’
- n= Value at POR reset
DS30559A-page 22
Preliminary
© 1996 Microchip Technology Inc.