PIC16F87XA
DS39582B-page 10
2003 Microchip Technology Inc.
TABLE 1-3:
PIC16F874A/877A PINOUT DESCRIPTION
Pin Name
PDIP
Pin#
PLCC
Pin#
TQFP
Pin#
QFN
Pin#
I/O/P
Type
Buffer
Type
Description
OSC1/CLKI
OSC1
CLKI
13
14
30
32
I
I
ST/CMOS
(4)
Oscillator crystal or external clock input.
Oscillator crystal input or external clock source
input. ST buffer when configured in RC mode;
otherwise CMOS.
External clock source input. Always associated
with pin function OSC1 (see OSC1/CLKI,
OSC2/CLKO pins).
OSC2/CLKO
OSC2
CLKO
14
15
31
33
O
O
—
Oscillator crystal or clock output.
Oscillator crystal output.
Connects to crystal or resonator in Crystal
Oscillator mode.
In RC mode, OSC2 pin outputs CLKO, which
has 1/4 the frequency of OSC1 and denotes the
instruction cycle rate.
MCLR/V
PP
MCLR
V
PP
1
2
18
18
I
P
ST
Master Clear (input) or programming voltage (output).
Master Clear (Reset) input. This pin is an active
low Reset to the device.
Programming voltage input.
PORTA is a bidirectional I/O port.
RA0/AN0
RA0
AN0
2
3
19
19
I/O
I
TTL
Digital I/O.
Analog input 0.
RA1/AN1
RA1
AN1
3
4
20
20
I/O
I
TTL
Digital I/O.
Analog input 1.
RA2/AN2/V
REF
-/CV
REF
RA2
AN2
V
REF
-
CV
REF
4
5
21
21
I/O
I
I
O
TTL
Digital I/O.
Analog input 2.
A/D reference voltage (Low) input.
Comparator V
REF
output.
RA3/AN3/V
REF
+
RA3
AN3
V
REF
+
5
6
22
22
I/O
I
I
TTL
Digital I/O.
Analog input 3.
A/D reference voltage (High) input.
RA4/T0CKI/C1OUT
RA4
T0CKI
C1OUT
6
7
23
23
I/O
I
O
ST
Digital I/O – Open-drain when configured as
output.
Timer0 external clock input.
Comparator 1 output.
RA5/AN4/SS/C2OUT
RA5
AN4
SS
C2OUT
7
8
24
24
I/O
I
I
O
TTL
Digital I/O.
Analog input 4.
SPI slave select input.
Comparator 2 output.
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.
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