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ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller SOIC 28 8-Bit 40 MHz I/O number 25
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PIC18F2220/2320/4220/4320
DS39599G-page 14 © 2007 Microchip Technology Inc.
TABLE 1-3: PIC18F4220/4320 PINOUT I/O DESCRIPTIONS
Pin Name
Pin Number
Pin
Type
Buffer
Type
Description
PDIP TQFP QFN
MCLR
/VPP/RE3
MCLR
VPP
RE3
11818
I
P
I
ST
ST
Master Clear (input) or programming voltage (input).
Master Clear (Reset) input. This pin is an active-low
Reset to the device.
Programming voltage input.
Digital input.
OSC1/CLKI/RA7
OSC1
CLKI
RA7
13 30 32
I
I
I/O
ST
CMOS
TTL
Oscillator crystal or external clock input.
Oscillator crystal input or external clock source input.
ST buffer when configured in RC mode, CMOS otherwise.
External clock source input. Always associated with
pin function OSC1. (See related OSC1/CLKI,
OSC2/CLKO pins.)
General purpose I/O pin.
OSC2/CLKO/RA6
OSC2
CLKO
RA6
14 31 33
O
O
I/O
—
—
TTL
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.
General purpose I/O pin.
PORTA is a bidirectional I/O port.
RA0/AN0
RA0
AN0
21919
I/O
I
TTL
Analog
Digital I/O.
Analog input 0.
RA1/AN1
RA1
AN1
32020
I/O
I
TTL
Analog
Digital I/O.
Analog input 1.
RA2/AN2/V
REF-/CVREF
RA2
AN2
V
REF-
CV
REF
42121
I/O
I
I
O
TTL
Analog
Analog
Analog
Digital I/O.
Analog input 2.
A/D reference voltage (low) input.
Comparator reference voltage output.
RA3/AN3/V
REF+
RA3
AN3
V
REF+
52222
I/O
I
I
TTL
Analog
Analog
Digital I/O.
Analog input 3.
A/D reference voltage (high) input.
RA4/T0CKI/C1OUT
RA4
T0CKI
C1OUT
62323
I/O
I
O
ST/OD
ST
—
Digital I/O. Open drain when configured as output.
Timer0 external clock input.
Comparator 1 output.
RA5/AN4/SS
/LVDIN/
C2OUT
RA5
AN4
SS
LVDIN
C2OUT
72424
I/O
I
I
I
O
TTL
Analog
TTL
Analog
—
Digital I/O.
Analog input 4.
SPI slave select input.
Low-Voltage Detect input.
Comparator 2 output.
RA6 See the OSC2/CLKO/RA6 pin.
RA7 See the OSC1/CLKI/RA7 pin.
Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output
ST = Schmitt Trigger input with CMOS levels I = Input
O = Output P = Power
OD = Open-drain (no diode to V
DD)
Note 1: Alternate assignment for CCP2 when CCP2MX is cleared.
2: Default assignment for CCP2 when CCP2MX (CONFIG3H<0>) is set.