6

7593GS–AVR–03/08

AT90USB64/128

The AT90USB64/128 provides the following features: 64/128K bytes of In-System Programma-

ble Flash with Read-While-Write capabilities, 2K/4K bytes EEPROM, 4K/8K bytes SRAM, 48

general purpose I/O lines, 32 general purpose working registers, Real Time Counter (RTC), four

flexible Timer/Counters with compare modes and PWM, one USART, a byte oriented 2-wire

Serial Interface, a 8-channels, 10-bit ADC with optional differential input stage with programma-

ble gain, programmable Watchdog Timer with Internal Oscillator, an SPI serial port, IEEE std.

1149.1 compliant JTAG test interface, also used for accessing the On-chip Debug system and

programming and six software selectable power saving modes. The Idle mode stops the CPU

while allowing the SRAM, Timer/Counters, SPI port, and interrupt system to continue function-

ing. The Power-down mode saves the register contents but freezes the Oscillator, disabling all

other chip functions until the next interrupt or Hardware Reset. In Power-save mode, the asyn-

chronous timer continues to run, allowing the user to maintain a timer base while the rest of the

device is sleeping. The ADC Noise Reduction mode stops the CPU and all I/O modules except

Asynchronous Timer and ADC, to minimize switching noise during ADC conversions. In Standby

mode, the Crystal/Resonator Oscillator is running while the rest of the device is sleeping. This

allows very fast start-up combined with low power consumption. In Extended Standby mode,

both the main Oscillator and the Asynchronous Timer continue to run.

The device is manufactured using Atmel’s high-density nonvolatile memory technology. The On-

chip ISP Flash allows the program memory to be reprogrammed in-system through an SPI serial

interface, by a conventional nonvolatile memory programmer, or by an On-chip Boot program

running on the AVR core. The boot program can use any interface to download the application

program in the application Flash memory. Software in the Boot Flash section will continue to run

while the Application Flash section is updated, providing true Read-While-Write operation. By

combining an 8-bit RISC CPU with In-System Self-Programmable Flash on a monolithic chip,

the Atmel AT90USB64/128 is a powerful microcontroller that provides a highly flexible and cost

effective solution to many embedded control applications.

The AT90USB64/128 AVR is supported with a full suite of program and system development

tools including: C compilers, macro assemblers, program debugger/simulators, in-circuit emula-

tors, and evaluation kits.

2.2

Pin Descriptions

2.2.1

VCC

Digital supply voltage.

2.2.2

GND

Ground.

2.2.3

Port A (PA7..PA0)

Port A is an 8-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 AT90USB64/128 as listed on

page 79.