PIC16F636-I/P Microchip Technology Inc., PIC16F636-I/P Datasheet - Page 23

• Manufacturer Part Number: PIC16F636-I/P
• Description: 14 PIN, 3.5 KB FLASH, 128 RAM, 12 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F636-I/P

• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 12
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 14-pin PDIP
• Programmable Memory: 3.5K Bytes
• Ram Size: 128 Bytes
• Speed: 20 MHz
• Timers: 1-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

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-up/pull-downs on PORTA
REGISTER 2-2:
© 2005 Microchip Technology Inc.
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/Pull-down Enable bit
1 = PORTA pull-ups/pull-downs are disabled
0 = PORTA pull-ups/pull-downs 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
PS<2:0>: Prescaler Rate Select bits
Legend:
R = Readable bit
- n = Value at POR
Bit Value TMR0 Rate WDT Rate
R/W-1
RAPU
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
PIC12F635/PIC16F636/639
1 : 1
1 : 2
1 : 4
1 : 8
1 : 16
1 : 32
1 : 64
1 : 128
Preliminary
W = Writable bit
‘1’ = Bit is set
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
(OPTION_REG<3>).
“Prescaler”.
R/W-1
PS2
the
PSA
x = Bit is unknown
R/W-1
PS1
See
DS41232B-page 21
bit
Section 5.4
to
R/W-1
PS0
bit 0
‘1’