
PIC16CR7X
DS21993C-page 10
2007 Microchip Technology Inc.
TABLE 1-3:
PIC16CR74 AND PIC16CR77 PINOUT DESCRIPTION
Pin Name
PDIP
Pin#
PLCC
Pin#
QFP
Pin#
I/O/P
Type
Buffer
Type
Description
OSC1/CLKIN
OSC1
CLKIN
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/CLKIN, OSC2/CLKOUT
pins).
OSC2/CLKOUT
OSC2
CLKOUT
14
15
31
O
—
Oscillator crystal or clock output.
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
1
2
18
I
ST
Master Clear (Reset) input. This pin is an active low
Reset to the device.
PORTA is a bidirectional I/O port.
RA0/AN0
RA0
AN0
23
19
I/O
I
TTL
Digital I/O.
Analog input 0.
RA1/AN1
RA1
AN1
34
20
I/O
I
TTL
Digital I/O.
Analog input 1.
RA2/AN2
RA2
AN2
45
21
I/O
I
TTL
Digital I/O.
Analog input 2.
RA3/AN3/VREF
RA3
AN3
VREF
56
22
I/O
I
TTL
Digital I/O.
Analog input 3.
A/D reference voltage input.
RA4/T0CKI
RA4
T0CKI
67
23
I/O
I
ST
Digital I/O – Open drain when configured as output.
Timer0 external clock input.
RA5/AN4/SS
RA5
AN4
SS
78
24
I/O
I
TTL
Digital I/O.
Analog input 4.
SPI slave select input.
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 an external interrupt.
2:
This buffer is a Schmitt Trigger input when used in Serial Verify 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.