PIC16F819 Microchip Technology Inc., PIC16F819 Datasheet - Page 19

• Manufacturer Part Number: PIC16F819
• Description: 18/20-pin Enhanced Flash Microcontrollers With Nanowatt Technology
• Manufacturer: Microchip Technology Inc.

2.2.2.2
The OPTION_REG register is a readable and writable
register that contains various control bits to configure
the TMR0 prescaler/WDT postscaler (single assign-
able register known also as the prescaler), the external
INT interrupt, TMR0 and the weak pull-ups on PORTB.
REGISTER 2-2:
 2004 Microchip Technology Inc.
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2-0
OPTION_REG Register
OPTION_REG: OPTION REGISTER (ADDRESS 81h, 181h)
bit 7
RBPU
1 = PORTB pull-ups are disabled
0 = PORTB pull-ups are enabled by individual port latch values
INTEDG: Interrupt Edge Select bit
1 = Interrupt on rising edge of RB0/INT pin
0 = Interrupt on falling edge of RB0/INT pin
T0CS: TMR0 Clock Source Select bit
1 = Transition on T0CKI pin
0 = Internal instruction cycle clock (CLKO)
T0SE: TMR0 Source Edge Select bit
1 = Increment on high-to-low transition on T0CKI pin
0 = Increment on low-to-high transition on 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
Bit Value TMR0 Rate WDT Rate
R/W-1
RBPU
000
001
010
011
100
101
110
111
:
PORTB Pull-up Enable bit
INTEDG
R/W-1
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
R/W-1
T0CS
W = Writable bit
‘1’ = Bit is set
R/W-1
T0SE
Note:
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
R/W-1
To achieve a 1:1 prescaler assignment for
the TMR0 register, assign the prescaler to
the Watchdog Timer.
PSA
PIC16F818/819
R/W-1
PS2
x = Bit is unknown
R/W-1
PS1
DS39598E-page 17
R/W-1
PS0
bit 0