PIC16F87X
TABLE 1-2:
Pin Name
OSC1/CLKIN
OSC2/CLKOUT
PIC16F874 AND PIC16F877 PINOUT DESCRIPTION
DIP
Pin#
13
14
PLCC
Pin#
14
15
QFP
Pin#
30
31
I/O/P
Type
I
O
Buffer
Type
ST/CMOS
(4)
—
Description
Oscillator crystal input/external clock source input.
Oscillator crystal output. Connects to crystal or resonator
in crystal oscillator mode. In RC mode, OSC2 pin outputs
CLKOUT which has 1/4 the frequency of OSC1, and
denotes the instruction cycle rate.
Master Clear (Reset) input or programming voltage input.
This pin is an active low RESET to the device.
PORTA is a bi-directional I/O port.
RA0 can also be analog input0.
RA1 can also be analog input1.
RA2 can also be analog input2 or negative
analog reference voltage.
RA3 can also be analog input3 or positive
analog reference voltage.
RA4 can also be the clock input to the Timer0 timer/
counter. Output is open drain type.
RA5 can also be analog input4 or the slave select for
the synchronous serial port.
PORTB is a bi-directional I/O port. PORTB can be soft-
ware programmed for internal weak pull-up on all inputs.
MCLR/V
PP
1
2
18
I/P
ST
RA0/AN0
RA1/AN1
RA2/AN2/V
REF
-
RA3/AN3/V
REF
+
RA4/T0CKI
RA5/SS/AN4
2
3
4
5
6
7
3
4
5
6
7
8
19
20
21
22
23
24
I/O
I/O
I/O
I/O
I/O
I/O
TTL
TTL
TTL
TTL
ST
TTL
RB0/INT
RB1
RB2
RB3/PGM
RB4
RB5
RB6/PGC
RB7/PGD
Legend: I = input
33
34
35
36
37
38
39
40
36
37
38
39
41
42
43
44
8
9
10
11
14
15
16
17
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
TTL/ST
(1)
TTL
TTL
TTL
TTL
TTL
TTL/ST
(2)
RB0 can also be the external interrupt pin.
RB3 can also be the low voltage programming input.
Interrupt-on-change pin.
Interrupt-on-change pin.
Interrupt-on-change pin or In-Circuit Debugger pin.
Serial programming clock.
Interrupt-on-change pin or In-Circuit Debugger pin.
Serial programming data.
P = power
ST = Schmitt Trigger input
TTL/ST
(2)
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.
DS30292C-page 8
2001 Microchip Technology Inc.
MICROCHIP [ MICROCHIP TECHNOLOGY ]
