PIC16F87XA
TABLE 1-3:
PIC16F874A/877A PINOUT DESCRIPTION
DIP
Pin#
PLCC
Pin#
QFP
Pin#
I/O/P
Type
Buffer
Type
Pin Name
Description
(4)
OSC1/CLKI
OSC1
Oscillator crystal or external clock input.
Oscillator crystal input or external clock source input.
ST buffer when configured in RC mode. Otherwise
CMOS.
13
14
30
I
ST/CMOS
CLKI
External clock source input. Always associated with
pin function OSC1 (see OSC1/CLKI, OSC2/CLKO
pins).
OSC2/CLKOUT
OSC2
14
15
31
O
—
Oscillator crystal or clock output.
Oscillator crystal output.
Connects to crystal or resonator in Crystal Oscillator
mode.
CLKO
In RC mode, OSC2 pin outputs CLKO, which has 1/4
the frequency of OSC1 and denotes the instruction
cycle rate.
MCLR/VPP
MCLR
1
2
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.
VPP
Programming voltage input.
PORTA is a bi-directional I/O port.
RA0/AN0
RA0
2
3
4
3
4
5
19
20
21
TTL
TTL
TTL
I/O
I
Digital I/O.
Analog input 0.
AN0
RA1/AN1
RA1
I/O
I
Digital I/O.
Analog input 1.
AN1
RA2/AN2/VREF-/CVREF
RA2
I/O
Digital I/O.
AN2
VREF-
CVREF
I
I
O
Analog input 2.
A/D reference voltage (Low) input.
Comparator VREF output.
RA3/AN3/VREF+
RA3
5
6
7
6
7
8
22
23
24
TTL
ST
I/O
I
I
Digital I/O.
Analog input 3.
A/D reference voltage (High) input.
AN3
VREF+
RA4/T0CKI/C1OUT
RA4
I/O
I
O
Digital I/O – Open drain when configured as output.
Timer0 external clock input.
Comparator 1 output.
T0CKI
C1OUT
RA5/SS/AN4/C2OUT
TTL
RA5
I/O
Digital I/O.
SS
AN4
I
I
SPI slave select input.
Analog input 4.
C2OUT
O
Comparator 2 output.
Legend: I = input
O = output
— = Not used
I/O = input/output
TTL = TTL input
P = power
ST = Schmitt Trigger 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.
DS39582A-page 10
AdvanceInformation
2001 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
