PIC16F676-I Datasheet, PDF (14/132 Pages) Microchip Technology – 14-Pin, Flash-Based 8-Bit CMOS Microcontrollers

PIC16F630/676
2.2.2.2 OPTION Register
The OPTION register is a readable and writable
register, which contains various control bits to
configure:
• TMR0/WDT prescaler
• External RA2/INT interrupt
• TMR0
• Weak pull-ups on PORTA
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”.
REGISTER 2-2:
OPTION_REG — OPTION REGISTER (ADDRESS: 81h)
R/W-1
RAPU
bit 7
R/W-1
INTEDG
R/W-1
T0CS
R/W-1
T0SE
R/W-1
PSA
R/W-1
PS2
R/W-1
PS1
R/W-1
PS0
bit 0
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2-0
RAPU: PORTA Pull-up Enable bit
1 = PORTA pull-ups are disabled
0 = PORTA pull-ups are enabled by individual PORT latch values
INTEDG: Interrupt Edge Select bit
1 = Interrupt on rising edge of RA2/INT pin
0 = Interrupt on falling edge of RA2/INT pin
T0CS: TMR0 Clock Source Select bit
1 = Transition on RA2/T0CKI pin
0 = Internal instruction cycle clock (CLKOUT)
T0SE: TMR0 Source Edge Select bit
1 = Increment on high-to-low transition on RA2/T0CKI pin
0 = Increment on low-to-high transition on RA2/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
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
DS40039F-page 14
 2010 Microchip Technology Inc.