3
2588F–AVR–06/2013
ATtiny261/461/861
1.1
Pin Descriptions
1.1.1
VCC
Supply voltage.
1.1.2
GND
Ground.
1.1.3
AVCC
Analog supply voltage. This is the supply voltage pin for the Analog-to-digital Converter (ADC),
the analog comparator, the Brown-Out Detector (BOD), the internal voltage reference and Port
A. It should be externally connected to VCC, even if some peripherals such as the ADC are not
used. If the ADC is used AVCC should be connected to VCC through a low-pass filter.
1.1.4
AGND
Analog ground.
1.1.5
Port A (PA7:PA0)
An 8-bit, bi-directional I/O port with internal pull-up resistors, individually selectable for each bit.
Output buffers have symmetrical drive characteristics with both high sink and source capability.
As inputs, port pins that are externally pulled low will source current if pull-up resistors have
been activated. Port 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 device, as listed on
page 63.
1.1.6
Port B (PB7:PB0)
An 8-bit, bi-directional I/O port with internal pull-up resistors, individually selectable for each bit.
Output buffers have symmetrical drive characteristics with both high sink and source capability.
As inputs, port pins that are externally pulled low will source current if pull-up resistors have
been activated. Port 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 device, as listed on
page 66.
1.1.7
RESET
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 and provided the reset pin has not been disabled. The min-
generate a reset.
The reset pin can also be used as a (weak) I/O pin.