PIC12F635/PIC16F636/639
4.2.4.2
RA1/C1IN-/VREF/ICSPCLK
4.2.4.3
RA2/T0CKI/INT/C1OUT
Figure 4-2 shows the diagram for this pin. The RA1 pin
is configurable to function as one of the following:
Figure 4-3 shows the diagram for this pin. The RA2 pin
is configurable to function as one of the following:
• a general purpose I/O
• a general purpose I/O
• an analog input to the comparator
• In-Circuit Serial Programming™ clock
• the clock input for Timer0
• an external edge-triggered interrupt
• a digital output from the comparator
FIGURE 4-2:
BLOCK DIAGRAM OF RA1
FIGURE 4-3:
BLOCK DIAGRAM OF RA2
Analog
Input Mode(1)
Data Bus
D
Q
Q
Data Bus
D
VDD
Q
Q
WR
CK
WPUDA
VDD
WR
CK
WPUDA
Weak
Weak
RAPU
RD
RAPU
RD
WPUDA
WPUDA
Weak
Weak
D
Q
Q
D
Q
Q
VSS
WR
WDA
CK
VSS
WR
CK
WDA
RD
RD
WDA
WDA
VDD
D
Q
Q
C1OUT
VDD
D
Q
Q
Enable
WR
PORTA
CK
WR
PORTA
CK
C1OUT
1
0
I/O pin
D
Q
Q
I/O pin
D
Q
Q
WR
TRISA
CK
VSS
WR
TRISA
CK
VSS
Analog
Input Mode(1)
RD
TRISA
RD
TRISA
RD
PORTA
RD
PORTA
D
Q
Q
D
Q
Q
Q
Q
D
CK
WR
IOCA
Q
Q
D
CK
WR
IOCA
Q1
EN
RD
IOCA
EN
Q1
D
RD
IOCA
D
EN
Interrupt-on-
change
EN
Interrupt-on-
change
RD PORTA
RD PORTA
To Comparator
To Timer0
To INT
Note 1: Comparator mode determines Analog Input mode.
© 2007 Microchip Technology Inc.
DS41232D-page 53
MICROCHIP [ MICROCHIP ]
