AT90USB82/162

Pin Descriptions

VCC

Digital supply voltage.

GND

Ground.

Port 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 AT90USB82/162 as listed on

page 71.

Port C (PC7..PC0)

Port C is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The

Port C output buffers have symmetrical drive characteristics with both high sink and source

capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up

resistors are activated. The Port C pins are tri-stated when a reset condition becomes active,

even if the clock is not running.

Port C also serves the functions of various special features of the AT90USB82/162 as listed on

page 73.

Port D (PD7..PD0)

Port D serves as analog inputs to the analog comparator.

Port D also serves as an 8-bit bi-directional I/O port, if the analog comparator is not used (con-

cerns PD2/PD1 pins). Port pins can provide 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.

D-/SDATA

USB Full Speed Negative Data Upstream Port / Data port for PS/2

D+/SCK

USB Full Speed Positive Data Upstream Port / Clock port for PS/2

UGND

USB Ground.

UVCC

USB Pads Internal Regulator Input supply voltage.

UCAP

USB Pads Internal Regulator Output supply voltage. Should be connected to an external capac-

itor (1µF).

RESET/PC1/dW

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 page

47. Shorter pulses are not guaranteed to generate a reset. This pin alternatively serves as

debugWire channel or as generic I/O.

XTAL1

Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.

XTAL2/PC0

Output from the inverting Oscillator amplifier if enabled by Fuse. Also serves as a generic I/O.