
PIC16F87XA
DS39582A-page 10
Advance Information
2001 Microchip Technology Inc.
TABLE 1-3:
PIC16F874A/877A PINOUT DESCRIPTION
Pin Name
DIP
Pin#
PLCC
Pin#
QFP
Pin#
I/O/P
Type
Buffer
Type
Description
OSC1/CLKI
OSC1
CLKI
13
14
30
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).
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.
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 bi-directional I/O port.
OSC2/CLKOUT
OSC2
CLKO
14
15
31
O
—
MCLR/V
PP
MCLR
V
PP
1
2
18
I/P
ST
RA0/AN0
RA0
AN0
RA1/AN1
RA1
AN1
RA2/AN2/V
REF
-/CV
REF
RA2
AN2
V
REF
-
CV
REF
RA3/AN3/V
REF
+
RA3
AN3
V
REF
+
RA4/T0CKI/C1OUT
RA4
T0CKI
C1OUT
RA5/SS/AN4/C2OUT
RA5
SS
AN4
C2OUT
Legend:
I = input
2
3
19
I/O
I
TTL
Digital I/O.
Analog input 0.
3
4
20
I/O
I
TTL
Digital I/O.
Analog input 1.
4
5
21
I/O
I
I
O
TTL
Digital I/O.
Analog input 2.
A/D reference voltage (Low) input.
Comparator V
REF
output.
5
6
22
I/O
I
I
TTL
Digital I/O.
Analog input 3.
A/D reference voltage (High) input.
6
7
23
I/O
I
O
ST
Digital I/O
–
Open drain when configured as output.
Timer0 external clock input.
Comparator 1 output.
7
8
24
I/O
I
I
O
TTL
Digital I/O.
SPI slave select input.
Analog input 4.
Comparator 2 output.
P = power
ST = Schmitt Trigger input
O = output
—
= Not used
I/O = input/output
TTL = TTL input
Note 1:
This buffer is a Schmitt Trigger input when configured as an 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 as general purpose I/O and a TTL input when used in the Parallel
Slave Port mode (for interfacing to a microprocessor bus).
4:
This buffer is a Schmitt Trigger input when configured in RC oscillator mode and a CMOS input otherwise.