AT90USB646 datasheet(203/434 Pages) ATMEL

203 / 434 page

203

7593A–AVR–02/06

AT90USB64/128

• Bit 3 – USBSn: Stop Bit Select

This bit selects the number of stop bits to be inserted by the Transmitter. The Receiver ignores

this setting.

• Bit 2:1 – UCSZn1:0: Character Size

The UCSZn1:0 bits combined with the UCSZn2 bit in UCSRnB sets the number of data bits

(Character SiZe) in a frame the Receiver and Transmitter use.

• Bit 0 – UCPOLn: Clock Polarity

This bit is used for synchronous mode only. Write this bit to zero when asynchronous mode is

used. The UCPOLn bit sets the relationship between data output change and data input sample,

and the synchronous clock (XCKn).

18.9.5

USART Baud Rate Registers – UBRRLn and UBRRHn

• Bit 15:12 – Reserved Bits

Table 18-6.

USBS Bit Settings

USBSn

Stop Bit(s)

01-bit

12-bit

Table 18-7.

UCSZn Bits Settings

UCSZn2

UCSZn1

UCSZn0

Character Size

000

5-bit

001

6-bit

010

7-bit

011

8-bit

100

Reserved

101

Reserved

110

Reserved

111

9-bit

Table 18-8.

UCPOLn Bit Settings

UCPOLn

Transmitted Data Changed (Output

of TxDn Pin)

Received Data Sampled (Input on

RxDn Pin)

Rising XCKn Edge

Falling XCKn Edge

Rising XCKn Edge

Bit

151413

121110

––––

UBRR[11:8]

UBRRHn

UBRR[7:0]

UBRRLn

7654

Read/Write

RRRR

R/W

Initial Value

0000

AT90USB646 Datasheet(PDF) 203 Page - ATMEL Corporation

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