Datasheet

PIC14000
DS40122B-page 18
Preliminary
 1996 Microchip Technology Inc.
4.2.2.2 OPTION REGISTER
The OPTION register (Address 81h) is a readable and
writable register which contains various control bits to
configure the TMR0/WDT prescaler, TMR0, and the
weak pull-ups on PORTC<5:0>. Bit 6 is reserved.
Note: To achieve a 1:1 prescaler assignment,
assign the prescaler to the WDT (PSA=1)
FIGURE 4-4: OPTION REGISTER
RCPU: PORTC pull-up enable
PSA PS2 PS1 PS0
R/W R/W R/W R/W R/W R/W R/W R/W
bit0
RCPU r T0CS T0SE
bit7
PS2 PS1 PS0
PSA: Prescaler assignment bit
T0SE: TMR0 source edge
T0CS: TMR0 clock source
PRESCALER VALUE
0
0
0
0
1
1
1
0
0
1
1
0
0
1
0
1
0
1
0
1
0
1 : 2
1 : 4
1 : 8
1 : 16
1 : 32
1 : 64
1 : 128
1 : 256
1 : 1
1 : 2
1 : 4
1 : 8
1 : 16
1 : 32
1 : 64
1 : 128
Reserved. This bit should be programmed as a ‘1’. Use of this bit as
Address: 81h
POR value: FFh
W: Writable
R: Readable
U: Unimplemented.
Read as '0'
TMR0 RATE WDT RATE
1 = Prescaler assigned to the WDT
0 = Prescaler assigned to TMR0
1 = Increment on high-to-low transition on RC3/T0CKI pin
0 = Increment on low-to-high transition on RC3/T0CKI pin
1 = Transition on RC3/T0CKI pin
0 = Internal instruction cycle clock (CLKOUT)
1 = PORTC pull-ups are disabled overriding any port latch value (RC<5:0> only)
0 = PORTC pull-ups are enabled by individual port-latch values (RC<5:0>)
PS2:PS0
111
Register: OPTION
general purpose read/write is not recommended since this may affect
upward compatibility with future products.