PIC14000 Datasheet, PDF (18/153 Pages) Microchip Technology – 28-Pin Programmable Mixed Signal Controller

PIC14000
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
R/W
RCPU
bit7
R/W
r
R/W R/W R/W R/W R/W R/W
T0CS T0SE PSA PS2 PS1 PS0
bit0
Register: OPTION W: Writable
Address:
81h R: Readable
POR value:
FFh U: Unimplemented.
Read as '0'
PRESCALER VALUE
PS2:PS0 _{PS2 PS1 PS0}
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
PSA: Prescaler assignment bit
1 = Prescaler assigned to the WDT
0 = Prescaler assigned to TMR0
TMR0 RATE
1:2
1:4
1:8
1 : 16
1 : 32
1 : 64
1 : 128
1 : 256
WDT RATE
1:1
1:2
1:4
1:8
1 : 16
1 : 32
1 : 64
1 : 128
T0SE: TMR0 source edge
1 = Increment on high-to-low transition on RC3/T0CKI pin
0 = Increment on low-to-high transition on RC3/T0CKI pin
T0CS: TMR0 clock source
1 = Transition on RC3/T0CKI pin
0 = Internal instruction cycle clock (CLKOUT)
Reserved. This bit should be programmed as a ‘1’. Use of this bit as
general purpose read/write is not recommended since this may affect
upward compatibility with future products.
RCPU: PORTC pull-up enable
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>)
DS40122B-page 18
Preliminary
© 1996 Microchip Technology Inc.