PIC16F676 Microchip Technology Inc., PIC16F676 Datasheet - Page 14

• Manufacturer Part Number: PIC16F676
• Description: 14-pin, Flash-based 8-bit Cmos Microcontroller
• Manufacturer: Microchip Technology Inc.

PIC16F630/676
2.2.2.2
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
REGISTER 2-2:
DS40039E-page 12
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2-0
OPTION Register
OPTION_REG — OPTION REGISTER (ADDRESS: 81h)
bit 7
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
Legend:
R = Readable bit
- n = Value at POR
R/W-1
RAPU
Bit Value TMR0 Rate WDT Rate
000
001
010
011
100
101
110
111
INTEDG
R/W-1
1 : 2
1 : 4
1 : 8
1 : 16
1 : 32
1 : 64
1 : 128
1 : 256
R/W-1
T0CS
W = Writable bit
’1’ = Bit is set
1 : 1
1 : 2
1 : 4
1 : 8
1 : 16
1 : 32
1 : 64
1 : 128
R/W-1
T0SE
Note:
R/W-1
U = Unimplemented bit, read as ‘0’
’0’ = Bit is cleared
PSA
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.
R/W-1
PS2
© 2007 Microchip Technology Inc.
x = Bit is unknown
R/W-1
PS1
R/W-1
PS0
bit 0