Datasheet

 2001-2013 Microchip Technology Inc. DS39598F-page 7
PIC16F818/819
TABLE 1-2: PIC16F818/819 PINOUT DESCRIPTIONS
Pin Name
PDIP/
SOIC
Pin#
SSOP
Pin#
QFN
Pin#
I/O/P
Type
Buffer
Type
Description
PORTA is a bidirectional I/O port.
RA0/AN0
RA0
AN0
17 19 23
I/O
I
TTL
Analog
Bidirectional I/O pin.
Analog input channel 0.
RA1/AN1
RA1
AN1
18 20 24
I/O
I
TTL
Analog
Bidirectional I/O pin.
Analog input channel 1.
RA2/AN2/V
REF-
RA2
AN2
V
REF-
1126
I/O
I
I
TTL
Analog
Analog
Bidirectional I/O pin.
Analog input channel 2.
A/D reference voltage (low) input.
RA3/AN3/VREF+
RA3
AN3
V
REF+
2227
I/O
I
I
TTL
Analog
Analog
Bidirectional I/O pin.
Analog input channel 3.
A/D reference voltage (high) input.
RA4/AN4/T0CKI
RA4
AN4
T0CKI
3328
I/O
I
I
ST
Analog
ST
Bidirectional I/O pin.
Analog input channel 4.
Clock input to the TMR0 timer/counter.
RA5/MCLR
/VPP
RA5
MCLR
VPP
441
I
I
P
ST
ST
–
Input pin.
Master Clear (Reset). Input/programming
voltage input. This pin is an active-low Reset
to the device.
Programming threshold voltage.
RA6/OSC2/CLKO
RA6
OSC2
CLKO
15 17 20
I/O
O
O
ST
–
–
Bidirectional I/O pin.
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.
RA7/OSC1/CLKI
RA7
OSC1
CLKI
16 18 21
I/O
I
I
ST
ST/CMOS
(3)
–
Bidirectional I/O pin.
Oscillator crystal input.
External clock source input.
Legend: I = Input O = Output I/O = Input/Output P = Power
– = Not used TTL = TTL Input ST = Schmitt Trigger 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.