AT43USB320A_04 ATMEL [ATMEL Corporation], AT43USB320A_04 Datasheet - Page 17

• Manufacturer Part Number: AT43USB320A_04
• Description: Full-speed USB Microcontroller with an Embedded Hub
• Manufacturer: ATMEL [ATMEL Corporation]

USB Hub
USB Function
1443E–USB–4/04
All AT43USB320A I/O and peripherals, except for the USB hardware registers, are placed in
the I/O space. The I/O locations are accessed by the IN and OUT instructions transferring data
between the 32 general purpose working registers and the I/O space. I/O registers within the
address range $00 – $1F are directly bit-accessible using the SBI and CBI instructions. In
these registers, the value of single bits can be checked by using the SBIS and SBIC instruc-
tions. Refer to the instruction set documentations of the AVR for more details. When using the
I/O specific commands, IN and OUT, the I/O address $00 – $3F must be used. When address-
ing I/O registers as SRAM, $20 must be added to this address. All I/O register addresses
throughout this document are shown with the SRAM address in parentheses.
For compatibility with future devices, reserved bits should be written to zero if accessed.
Reserved I/O memory addresses should never be written.
A block diagram of the USB hardware of the AT43USB320A is shown in Figure 3. The USB
hub of the AT43USB320A has 5 downstream ports. The embedded function is permanently
attached to Port 5. Ports 1 through 4 are available as external ports. The actual number of
ports used is strictly defined by the firmware of the AT43USB320A and can vary from 0 to 4.
Because the exact configuration is defined by firmware, ports 1 to 4 may even function as per-
manently attached ports as long as the Hub Descriptor identifies them as such.
The embedded USB function has its own device address and has a default endpoint plus 2
other programmable endpoints with 8-byte FIFOs. Endpoints 1 - 3 can be programmed as
interrupt IN or OUT or bulk IN or OUT endpoints.
AT43USB320A
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