
PIC16C5X
DS30453D-page 30
Preliminary
2002 Microchip Technology Inc.
6.4
OPTION Register
The OPTION Register is a 6-bit wide, write-only regis-
ter 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 Reg-
ister. A RESET sets the OPTION<5:0> bits.
REGISTER 6-2:
OPTION REGISTER
U-0
W-1
—
T0CS
TOSE
PSA
PS2
PS1
PS0
bit 7
bit 0
bit 7-6:
Unimplemented: Read as ‘0’
bit 5:
T0CS: Timer0 clock source select bit
1
= Transition on T0CKI pin
0
= Internal instruction cycle clock (CLKOUT)
bit 4:
T0SE: Timer0 source edge select bit
1
= Increment on high-to-low transition on T0CKI pin
0
= Increment on low-to-high transition on 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
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
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