Datasheet

© 2007 Microchip Technology Inc. DS41270E-page 17
PIC10F220/222
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.
The OPTION register is not memory mapped and is
therefore only addressable by executing the OPTION
instruction, the contents of the W register will be trans-
ferred 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
and GPWU).
Note: If the T0CS bit is set to ‘1’, it will override
the TRIS function on the T0CKI pin.
REGISTER 4-2: OPTION REGISTER
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
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
bit 7 GPWU
: Enable Wake-up On Pin Change bit (GP0, GP1, GP3)
1 = Disabled
0 = Enabled
bit 6 GPPU
: Enable Weak Pull-ups bit (GP0, GP1, GP3)
1 = Disabled
0 = Enabled
bit 5 T0CS: Timer0 Clock Source Select bit
1 = Transition on T0CKI pin (overrides TRIS on the T0CKI pin)
0 = Transition on internal instruction cycle clock, F
OSC/4
bit 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
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
1 : 2
1 : 4
1 : 8
1 : 16
1 : 32
1 : 64
1 : 128
Bit Value Timer0 Rate WDT Rate