ATTIny2313-16MI ATMEL Corporation, ATTIny2313-16MI Datasheet - Page 134

• Manufacturer Part Number: ATTIny2313-16MI
• Description: 8-bit AVR Microcontroller with 2K Bytes In-System Programmable Flash
• Manufacturer: ATMEL Corporation

USART Baud Rate Registers –
UBRRL and UBRRH
134
ATtiny2313/V
Table 55. UCSZ Bits Settings
• Bit 0 – UCPOL: Clock Polarity
This bit is used for synchronous mode only. Write this bit to zero when asynchronous
mode is used. The UCPOL bit sets the relationship between data output change and
data input sample, and the synchronous clock (XCK).
Table 56. UCPOL Bit Settings
• Bit 15:12 – Reserved Bits
These bits are reserved for future use. For compatibility with future devices, these bit
must be written to zero when UBRRH is written.
• Bit 11:0 – UBRR11:0: USART Baud Rate Register
This is a 12-bit register which contains the USART baud rate. The UBRRH contains the
four most significant bits, and the UBRRL contains the eight least significant bits of the
USART baud rate. Ongoing transmissions by the Transmitter and Receiver will be cor-
rupted if the baud rate is changed. Writing UBRRL will trigger an immediate update of
the baud rate prescaler.
Bit
Read/Write
Initial Value
UCPOL
0
1
UCSZ2
0
0
0
0
1
1
1
1
Transmitted Data Changed (Output of
TxD Pin)
Rising XCK Edge
Falling XCK Edge
R/W
15
R
–
7
0
0
R/W
14
UCSZ1
R
–
6
0
0
0
0
1
1
0
0
1
1
R/W
13
R
–
5
0
0
R/W
12
R
–
4
0
0
UBRR[7:0]
UCSZ0
0
1
0
1
0
1
0
1
R/W
R/W
11
3
0
0
Received Data Sampled (Input on
RxD Pin)
Falling XCK Edge
Rising XCK Edge
R/W
R/W
Character Size
5-bit
6-bit
7-bit
8-bit
Reserved
Reserved
Reserved
9-bit
10
2
0
0
UBRR[11:8]
R/W
R/W
9
1
0
0
R/W
R/W
8
0
0
0
2543C–AVR–12/03
UBRRH
UBRRL