
2009 Microchip Technology Inc.
DS41236E-page 13
PIC12F508/509/16F505
TABLE 3-2:
PIC12F508/509 PINOUT DESCRIPTION
Name
Function
Input
Type
Output
Type
Description
GP0/ICSPDAT
GP0
TTL
CMOS Bidirectional I/O pin. Can be software programmed for internal
weak pull-up and wake-up from Sleep on pin change.
ICSPDAT
ST
CMOS In-Circuit Serial Programming data pin.
GP1/ICSPCLK
GP1
TTL
CMOS Bidirectional I/O pin. Can be software programmed for internal
weak pull-up and wake-up from Sleep on pin change.
ICSPCLK
ST
CMOS In-Circuit Serial Programming clock pin.
GP2/T0CKI
GP2
TTL
CMOS Bidirectional I/O pin.
T0CKI
ST
—
Clock input to TMR0.
GP3/MCLR/VPP
GP3
TTL
—
Input pin. Can be software programmed for internal weak
pull-up and wake-up from Sleep on pin change.
MCLR
ST
—
Master Clear (Reset). When configured as MCLR, this pin is
an active-low Reset to the device. Voltage on MCLR/VPP must
not exceed VDD during normal device operation or the device
will enter Programming mode. Weak pull-up always on if
configured as MCLR.
VPP
HV
—
Programming voltage input.
GP4/OSC2
GP4
TTL
CMOS Bidirectional I/O pin.
OSC2
—
XTAL
Oscillator crystal output. Connections to crystal or resonator in
Crystal Oscillator mode (XT and LP modes only, GPIO in other
modes).
GP5/OSC1/CLKIN
GP5
TTL
CMOS Bidirectional I/O pin.
OSC1
XTAL
—
Oscillator crystal input.
CLKIN
ST
—
External clock source input.
VDD
—
P
Positive supply for logic and I/O pins.
VSS
—
P
Ground reference for logic and I/O pins.
Legend: I = Input, O = Output, I/O = Input/Output, P = Power, — = Not used, TTL = TTL input,
ST = Schmitt Trigger input, HV = High Voltage