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 TMR1 clock input
• a crystal/resonator connection
• a clock input
FIGURE 4-6:
BLOCK DIAGRAM OF RA5
INTOSC
Mode
TMR1LPEN(1)
VDD
Data Bus
D
Q
Q
WR
CK
Weak
WPUA
RABPU
RD
WPUA
Oscillator
Circuit
OSC2
VDD
D
Q
Q
WR
PORTA
CK
I/O Pin
D
Q
Q
WR
TRISA
CK
VSS
INTOSC
Mode
RD
TRISA
(2)
RD
PORTA
D
Q
Q
Q
Q
D
CK
WR
IOCA
Q3
EN
RD
IOCA
D
EN
Interrupt-on-
Change
RD PORTA
To TMR1 or CLKGEN
Note 1: Timer1 LP Oscillator enabled.
2: When using Timer1 with LP oscillator, the
Schmitt Trigger is bypassed.
© 2007 Microchip Technology Inc.
DS41262D-page 67
MICROCHIP [ MICROCHIP ]
