1
Features
•8-bit AVR® Core with 83 ns Instruction Cycle Time
•16K Bytes ROM Program Memory
•512 Bytes SRAM
•32 x 8 General Purpose Working Registers
•20 Programmable I/O Port Pins
•Programmable Serial UART
•SPI Serial Interface
•One 8-bit Timer/ Counte r with Separate Prescale r
•One 16-bit Timer/Counter with Separate Prescaler
•External and Internal Interrupt Sources
•Programmable Watchdog Timer with On-chip Oscillator
•Bus-or Self-powered USB Hub with Four Downstream Ports
•One Attached Function Port with Three Endpoints
•Programmable 6/12 MHz Oscillator with PLL
•On-chip 3.3V Supply for USB
•42-pin SDIP and 48-lead TQFP Packages
Overview
The Atmel AT43USB321 is a single-chip m icrocontroller based USB hub with an
embedded function and a 16K byte masked ROM. 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 imple-
mented in the microcontoller’s firmware. To the USB host, the embedded function
appears as an atta ched por t of the hub with its own device a ddress an d endpoi nts.
The AT43USB321 can also be configured as a USB function without the hub.
The USB hardw are bloc k cons ists of a USB tr anscei ver, SI E, hub r epeat er, en dpoint
controllers, and an interface to the microcontro ller. The USB hardware interfaces to
the USB hos t at the tr ansactio n leve l. The CPU of the mic rocontr oller is base d on the
Atmel AVR microcontroller. The AVR architecture was developed to be programmed
in C efficiently and with maximum performance.
Full- sp eed USB
Hub/Functio n
Microcontroller
AT43USB321
Rev. 14 42A–08/99
AT43USB321
2
Figure 1. AT43USB321 Block Diagram
Development Support
The AT4USB321 uses the same program and development
tools as the Atmel AVR microcontrollers including: C com-
pilers, macro assemblers, program debuggers/ simulators,
in-circuit emulators. The AT43USB321 is binary compatible
with the AT43320 and the two share the same develop-
ment ki t, whi ch i nclu des f irmwa re s ou rce c ode fo r the m ost
common USB applications.
Applications
The attached diagram shows an application of the
AT43USB321 in a monitor as a hub with two embedded
functions: a monitor display controller and IR receiver. The
number of external downstream ports of the hub is pro-
gramma ble from one to four . The hub can be self-p owered
or bus-powered. In most cases, hubs in the monitors will be
self-powered because of the readily availability of the
power supply and its more versatility.
In this example, the AT 43USB32 1 interfac es to th e moni-
tor’s microcontroller, the host microcontroller, through an
I2C serial bus that supports two way communications such
as DDC2Bi. The firmware inside the AT43USB321 acts as
the trans la tor be twee n the hos t s y stem a nd the host mi cr o-
controller. This function can be performed without any
modific ation in the host micr ocontroll er’s firmware resul ting
in a very flexible way of adding USB capability in any moni-
tor. The IR receiver function is also implemented in
firmware also and can support any consumer type IR proto-
col that uses a frequency in the range of up to 52 kHz.
HUB AND
DEVICE
CONTROLLER
GENERAL PURPOSE IO
PORT4
PORT3
PORT2
PORT1
LFT
OSC1
OSC2
6/12M
DP0
DM0
PA[0:7]
PB[0:7]
PD0/RXD
PD1/TXD
PD2/INT0
PD3/INT1
CEXT
VCC
VSS
DP4
DM4
DP3
DM3
DP2
DM2
DP1
DM1
OVC
PWR
RST
OSC
&
PLL
SERIAL
INTERFACE
ENGINE
HUB
REPEATER
AT43USB321
3
Figure 2. Hub/Monitor/IR Chip Application
REMOTE
IR
UNIT
IR
XCVR IR
XCVR
HUB/MONITOR/IR
CHIP
UPSTREAM
PORT
DOWNSTREAM
PORTS
I C /UART
MONITOR
µC
TO USB HOST
TO USB DEVICES
2
© Atmel Corporation 1999.
Atmel Corporation makes no warranty for the use of its products, other than those expressly contained in the Company’s standard war-
ranty which is detailed in Atmel’s Terms and Conditions located on the Company’s web site. The Company assumes no responsibility for
any errors which may appear in this document, reserves the right to change devices or specifications detailed herein at any time without
notice, and does not make any commitment to update the information contained herein. No licenses to patents or other intellectual prop-
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not authorized for use as critical com ponents in life support devices or systems.
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1442A–08/99/xM
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