PIC12F508_1 Datasheet, PDF (24/98 Pages) Microchip Technology – 8/14-Pin, 8-Bit Flash Microcontrollers

PIC12F508/509/16F505
4.5 Option Register
The Option register is a 8-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 register.
A Reset sets the Option<7:0> bits.
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/RBPU and
GPWU/RBWU).
Note: If the T0CS bit is set to ‘1’, it will override
the TRIS function on the T0CKI pin.
REGISTER 4-3: OPTION REGISTER (PIC12F508/509)
W-1
W-1
W-1
W-1
W-1
W-1
W-1
W-1
GPWU GPPU T0CS T0SE
PSA
PS2
PS1
PS0
bit 7
bit 0
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2-0
GPWU: Enable Wake-up on Pin Change bit (GP0, GP1, GP3)
1 = Disabled
0 = Enabled
GPPU: Enable Weak Pull-ups bit (GP0, GP1, GP3)
1 = Disabled
0 = Enabled
T0CS: Timer0 Clock Source Select bit
1 = Transition on T0CKI pin (overrides TRIS on the T0CKI pin)
0 = Transition on internal instruction cycle clock, FOSC/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
PSA: Prescaler Assignment bit
1 = Prescaler assigned to the WDT
0 = Prescaler assigned to Timer0
PS<2:0>: Prescaler Rate Select bits
Bit Value Timer0 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
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
DS41236A-page 22
Preliminary
 2004 Microchip Technology Inc.