
5
2543L–AVR–08/10
ATtiny2313
Pin Descriptions
VCC
Digital supply voltage.
GND
Ground.
Port A (PA2..PA0)
Port A is a 3-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port A output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port A pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port A pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port A also serves the functions of various special features of the ATtiny2313 as listed on
pagePort B (PB7..PB0)
Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port B output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port B pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port B also serves the functions of various special features of the ATtiny2313 as listed on
pagePort D (PD6..PD0)
Port D is a 7-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port D output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port D pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port D also serves the functions of various special features of the ATtiny2313 as listed on
pageRESET
Reset input. A low level on this pin for longer than the minimum pulse length will generate a
reset, even if the clock is not running. The minimum pulse length is given in
Table 15 on page34. Shorter pulses are not guaranteed to generate a reset. The Reset Input is an alternate func-
tion for PA2 and dW.
XTAL1
Input to the inverting Oscillator amplifier and input to the internal clock operating circuit. XTAL1
is an alternate function for PA0.
XTAL2
Output from the inverting Oscillator amplifier. XTAL2 is an alternate function for PA1.