
2002 Microchip Technology Inc.
Preliminary
DS40143D-page 11
PIC16C55X
TABLE 3-1:
PIC16C55X PINOUT DESCRIPTION
Name
Pin Number
Pin
Type
Buffer
Type
PDIP
SOIC
SSOP
Description
OSC1/CLKIN
16
18
I
ST/CMOS Oscillator crystal input/external clock source output.
OSC2/CLKOUT
15
17
O
—
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.
MCLR/V
PP
4
I/P
ST
Master clear (Reset) input/programming voltage input.
This pin is an active low RESET to the device.
RA0
17
19
I/O
ST
Bi-directional I/O port
RA1
18
20
I/O
ST
Bi-directional I/O port
RA2
1
I/O
ST
Bi-directional I/O port
RA3
2
I/O
ST
Bi-directional I/O port
RA4/T0CKI
3
I/O
ST
Bi-directional I/O port or external clock input for TMR0.
Output is open drain type.
RB0/INT
6
7
I/O
TTL/ST(1)
Bi-directional I/O port can be software programmed for
internal weak pull-up. RB0/INT can also be selected as an
external interrupt pin.
RB1
7
8
I/O
TTL
Bi-directional I/O port can be software programmed for
internal weak pull-up.
RB2
8
9
I/O
TTL
Bi-directional I/O port can be software programmed for
internal weak pull-up.
RB3
9
10
I/O
TTL
Bi-directional I/O port can be software programmed for
internal weak pull-up.
RB4
10
11
I/O
TTL
Bi-directional I/O port can be software programmed for
internal weak pull-up. Interrupt-on-change pin.
RB5
11
12
I/O
TTL
Bi-directional I/O port can be software programmed for
internal weak pull-up. Interrupt-on-change pin.
RB6
12
13
I/O
TTL/ST(2)
Bi-directional I/O port can be software programmed for
internal weak pull-up. Interrupt-on-change pin. Serial pro-
gramming clock.
RB7
13
14
I/O
TTL/ST(2)
Bi-directional I/O port can be software programmed for
internal weak pull-up. Interrupt-on-change pin. Serial pro-
gramming data.
RC0(3)
18
I/O
TTL
Bi-directional I/O port input buffer.
RC1(3)
19
I/O
TTL
Bi-directional I/O port input buffer.
RC2(3)
20
I/O
TTL
Bi-directional I/O port input buffer.
RC3(3)
21
I/O
TTL
Bi-directional I/O port input buffer.
RC4(3)
22
I/O
TTL
Bi-directional I/O port input buffer.
RC5(3)
23
I/O
TTL
Bi-directional I/O port input buffer.
RC6(3)
24
I/O
TTL
Bi-directional I/O port input buffer.
RC7(3)
25
I/O
TTL
Bi-directional I/O port input buffer.
V
SS
5
5,6
P
—
Ground reference for logic and I/O pins.
V
DD
14
15,16
P
—
Positive supply for logic and I/O pins.
Legend:
O = Output
I/O = Input/output
P = Power
— = Not used
I = Input
ST = Schmitt Trigger input
TTL = TTL 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: PIC16C557 only.