3

8197CS–AVR–05/11

ATtiny261A/461A/861A

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.

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.

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.