PIC12F629/675
2.2.2.2
OPTION Register
Note: To achieve a 1:1 prescaler assignment for
TMR0, assign the prescaler to the WDT by
setting PSA bit to ‘1’ (OPTION<3>). See
Section 4.4 “Prescaler”.
The OPTION register is a readable and writable
register, which contains various control bits to
configure:
• TMR0/WDT prescaler
• External GP2/INT interrupt
• TMR0
• Weak pull-ups on GPIO
REGISTER 2-2:
R/W-1
OPTION_REG: OPTION REGISTER (ADDRESS: 81h)
R/W-1
R/W-1
T0CS
R/W-1
T0SE
R/W-1
PSA
R/W-1
PS2
R/W-1
PS1
R/W-1
PS0
GPPU
INTEDG
bit 7
bit 0
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
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2-0
GPPU: GPIO Pull-up Enable bit
1= GPIO pull-ups are disabled
0= GPIO pull-ups are enabled by individual PORT latch values
INTEDG: Interrupt Edge Select bit
1= Interrupt on rising edge of GP2/INT pin
0= Interrupt on falling edge of GP2/INT pin
T0CS: TMR0 Clock Source Select bit
1= Transition on GP2/T0CKI pin
0= Internal instruction cycle clock (CLKOUT)
T0SE: TMR0 Source Edge Select bit
1= Increment on high-to-low transition on GP2/T0CKI pin
0= Increment on low-to-high transition on GP2/T0CKI pin
PSA: Prescaler Assignment bit
1= Prescaler is assigned to the WDT
0= Prescaler is assigned to the TIMER0 module
PS2:PS0: Prescaler Rate Select bits
Bit Value TMR0 Rate WDT Rate
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
DS41190G-page 14
2010 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
