Overview
The Atmel AT43320 is a microcontroller-based USB hub with an embedded function. The USB hub has five downstream ports, one of which is permanently attached. Internally the AT43320 consists of a USB hub and function interface, a hub repeater, and a high-performance, efficient 8-bit RISC microcontroller. The hub and peripheral device controller function is implemented in the microcontroller’s firmware. To the USB host, the embedded function appears as an attached port of the hub with its own device address and endpoints. The AT43320 can also be configured as a USB function without the hub.

FEATUREs
• AVR® Microcontroller-based USB Hub and Function Controller
• One Upstream Port Plus Four External and One Attached Downstream Ports
• USB Hub with Two Endpoints
• Embedded USB Function with 3 Endpoints
• 32 Programmable I/O Port Pins
• High-performance and Low-power AVR RISC Microcontroller
• 120 Powerful Instructions – Most with 83 ns Execution Cycle Times
• 128K Bytes Program Memory Address Range
• 512 Bytes Internal SRAM
• 32 x 8 General-purpose Working Registers
• Programmable UART and SPI Serial Interface
• One 8-bit Timer/Counter with Separate Prescaler
• One 16-bit Timer/Counter with Separate Prescaler
• External and Internal Interrupt Sources
• Programmable Watchdog Timer
• Low-power Idle and Power-down Modes
• Programmable 6/12 MHz Oscillator with PLL
• On-chip 3.3V Power Supply
• 100-pin LQFP Package