PIC16F631_08 Datasheet, PDF (69/306 Pages) Microchip Technology – 20-Pin Flash-Based, 8-Bit CMOS Microcontrollers with nanoWatt Technology

PIC16F631/677/685/687/689/690
4.2.5.6 RA5/T1CKI/OSC1/CLKIN
Figure 4-6 shows the diagram for this pin. The
RA5/T1CKI/OSC1/CLKIN pin is configurable to
function as one of the following:
• a general purpose I/O
• a Timer1 clock input
• a crystal/resonator connection
• a clock input
FIGURE 4-6:
BLOCK DIAGRAM OF RA5
Data Bus
DQ
WR
WPUA
CK _Q
RD
WPUA
DQ
WR
PORTA
CK _Q
WR
TRISA
DQ
CK _Q
RD
TRISA
RD
PORTA
DQ
WR
IOCA
CK _Q
RD
IOCA
Interrupt-on-
Change
INTOSC
Mode
TMR1LPEN⁽¹⁾
VDD
Weak
RABPU
Oscillator
Circuit
OSC2
VDD
INTOSC
Mode
I/O Pin
VSS
(2)
QD
EN
Q3
QD
EN
RD PORTA
To TMR1 or CLKGEN
Note
1: Timer1 LP Oscillator enabled.
2: When using Timer1 with LP oscillator, the
Schmitt Trigger is bypassed.
© 2008 Microchip Technology Inc.
DS41262E-page 67