PIC16F818/819
TABLE 1-2:
Pin Name
PIC16F818/819 PINOUT DESCRIPTIONS
PDIP/
SSOP QFN I/O/P
Pin# Pin# Type
Buffer
Type
SOIC
Pin#
Description
PORTA is a bidirectional I/O port.
RA0/AN0
RA0
17
18
1
19
20
1
23
24
26
I/O
I
TTL
Analog
Bidirectional I/O pin.
Analog input channel 0.
AN0
RA1/AN1
RA1
I/O
I
TTL
Analog
Bidirectional I/O pin.
Analog input channel 1.
AN1
RA2/AN2/VREF-
RA2
I/O
TTL
Bidirectional I/O pin.
AN2
VREF-
I
I
Analog
Analog
Analog input channel 2.
A/D reference voltage (low) input.
RA3/AN3/VREF+
RA3
2
3
4
2
3
4
27
28
1
I/O
I
I
TTL
Analog
Analog
Bidirectional I/O pin.
Analog input channel 3.
A/D reference voltage (high) input.
AN3
VREF+
RA4/AN4/T0CKI
RA4
I/O
I
I
ST
Analog
ST
Bidirectional I/O pin.
Analog input channel 4.
Clock input to the TMR0 timer/counter.
AN4
T0CKI
RA5/MCLR/VPP
RA5
I
I
ST
ST
Input pin.
MCLR
Master Clear (Reset). Input/programming
voltage input. This pin is an active-low Reset
to the device.
VPP
P
–
Programming threshold voltage.
RA6/OSC2/CLKO
RA6
15
16
17
20
I/O
O
ST
–
Bidirectional I/O pin.
OSC2
Oscillator crystal output. Connects to crystal or
resonator in Crystal Oscillator mode.
In RC mode, this pin outputs CLKO signal
which has 1/4 the frequency of OSC1 and
denotes the instruction cycle rate.
CLKO
O
–
RA7/OSC1/CLKI
RA7
18
O
21
I/O
I
I
ST
ST/CMOS(3)
–
Bidirectional I/O pin.
Oscillator crystal input.
External clock source input.
OSC1
CLKI
Legend:
I
= Input
= Output
I/O = Input/Output
ST = Schmitt Trigger Input
P = Power
– = Not used
TTL = TTL Input
Note 1: This buffer is a Schmitt Trigger input when configured as the external interrupt.
2: This buffer is a Schmitt Trigger input when used in Serial Programming mode.
3: This buffer is a Schmitt Trigger input when configured in RC Oscillator mode and a CMOS input otherwise.
2004 Microchip Technology Inc.
DS39598E-page 7
MICROCHIP [ MICROCHIP ]
