AT90USB646 datasheet(282/459 Pages) ATMEL

282 / 459 page

282

7593H–AVR–11/08

ATmega32U6/AT90USB64/128

• 7-5 - Reserved

The value read from these bits is always 0. Do not set these bits.

• 4 - FNCERR -Frame Number CRC Error Flag

Set by hardware when a corrupted Frame Number in start of frame packet is received.

This bit and the SOFI interrupt are updated at the same time.

• 3-0 - Reserved

The value read from these bits is always 0. Do not set these bits.

22.18.2

USB device endpoint registers

• 7-3 - Reserved

The value read from these bits is always 0. Do not set these bits.

• 2-0 - EPNUM2:0 Endpoint Number Bits

Load by software to select the number of the endpoint which shall be accessed by the CPU. See

Section 22.5, page 268 for more details.

EPNUM = 111b is forbidden.

• 7 - Reserved

The value read from these bits is always 0. Do not set these bits.

• 6-0 - EPRST6:0 - Endpoint FIFO Reset Bits

Set to reset the selected endpoint FIFO prior to any other operation, upon hardware reset or

when an USB bus reset has been received. See Section 22.3, page 267 for more information

Then, clear by software to complete the reset operation and start using the endpoint.

Bit

76543210

---

FNCERR

----

UDMFN

Read/W

rite

Initial

Value

00000000

Bit

765432

EPNUM2:0

UENUM

Read/Write

RRRRR

R/W

Initial Value

000000

Bit

765432

EPRST6

EPRST5

EPRST4

EPRST3

EPRST2

EPRST1

EPRST0

UERST

Read/Write

R/W

Initial Value

000000

AT90USB646 Datasheet(PDF) 282 Page - ATMEL Corporation

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