PIC16LF720_11 Datasheet, PDF (22/244 Pages) Microchip Technology – 20-Pin Flash Microcontrollers with nanoWatt XLP Technology

PIC16(L)F720/721
2.2.2.2 OPTION register
The OPTION register, shown in Register 2-2, is a
readable and writable register, which contains various
control bits to configure:
• Software programmable prescaler for the Timer0/
WDT
• External RA2/INT interrupt
• Timer0
• Weak pull-ups on PORTA or PORTB
Note:
To achieve a 1:1 prescaler assignment for
Timer0, assign the prescaler to the WDT
by setting the PSA bit of the OPTION
register to ‘1’. Refer to Section 12.1.3
“Software Programmable Prescaler”.
REGISTER 2-2: OPTION_REG: OPTION REGISTER
R/W-1
RABPU
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
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
RABPU: PORTA or PORTB Pull-up Enable bit
1 = PORTA or PORTB pull-ups are disabled
0 = PORTA or PORTB pull-ups are enabled by individual bits in the WPUB register
INTEDG: Interrupt Edge Select bit
1 = Interrupt on rising edge of RA2/INT pin
0 = Interrupt on falling edge of RA2/INT pin
T0CS: Timer0 Clock Source Select bit
1 = Transition on RA2/T0CKI pin
0 = Internal instruction cycle clock (FOSC/4)
T0SE: Timer0 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
PS<2:0>: Prescaler Rate Select bits
Bit Value Timer0 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
DS41430B-page 22
Preliminary
 2011 Microchip Technology Inc.