Microchip Technology AC244045 データシート
PIC16F72X/PIC16LF72X
DS41341E-page 28
© 2009 Microchip Technology Inc.
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:
readable and writable register, which contains various
control bits to configure:
• Timer0/WDT prescaler
• External RB0/INT interrupt
• Timer0
• Weak pull-ups on PORTB
Note:
To achieve a 1:1 prescaler assignment for
Timer0, assign the prescaler to the WDT by
setting PSA bit of the OPTION register to
‘1’. Refer to Section 12.3 “Timer1
Prescaler”.
Timer0, assign the prescaler to the WDT by
setting PSA bit of the OPTION register to
‘1’. Refer to Section 12.3 “Timer1
Prescaler”.
REGISTER 2-2:
OPTION_REG: OPTION REGISTER
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
R/W-1
RBPU
INTEDG
T0CS
T0SE
PSA
PS2
PS1
PS0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
RBPU: PORTB Pull-up Enable bit
1
= PORTB pull-ups are disabled
0
= PORTB pull-ups are enabled by individual bits in the WPUB register
bit 6
INTEDG: Interrupt Edge Select bit
1
= Interrupt on rising edge of RB0/INT pin
0
= Interrupt on falling edge of RB0/INT pin
bit 5
T0CS: Timer0 Clock Source Select bit
1
= Transition on RA4/T0CKI pin
0
= Internal instruction cycle clock (F
OSC
/4)
bit 4
T0SE: Timer0 Source Edge Select bit
1
= Increment on high-to-low transition on RA4/T0CKI pin
0
= Increment on low-to-high transition on RA4/T0CKI pin
bit 3
PSA: Prescaler Assignment bit
1
= Prescaler is assigned to the WDT
0
= Prescaler is assigned to the Timer0 module
bit 2-0
PS<2:0>: Prescaler Rate Select bits
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 : 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
1 : 2
1 : 4
1 : 8
1 : 16
1 : 32
1 : 64
1 : 128
Bit Value
Timer0 Rate
WDT Rate