ATmega8(L)
TXB8 is the ninth data bit in the character to be transmitted when operating with serial
frames with nine data bits. Must be written before writing the low bits to UDR.
USART Control and Status
Register C – UCSRC
Bit
7
URSEL
R/W
1
6
UMSEL
R/W
0
5
UPM1
R/W
0
4
UPM0
R/W
0
3
USBS
R/W
0
2
UCSZ1
R/W
1
1
UCSZ0
R/W
1
0
UCPOL
R/W
0
UCSRC
Read/Write
Initial Value
The UCSRC Register shares the same I/O location as the UBRRH Register. See the
“Accessing UBRRH/UCSRC Registers” on page 149 section which describes how to
access this register.
• Bit 7 – URSEL: Register Select
This bit selects between accessing the UCSRC or the UBRRH Register. It is read as
one when reading UCSRC. The URSEL must be one when writing the UCSRC.
• Bit 6 – UMSEL: USART Mode Select
This bit selects between Asynchronous and Synchronous mode of operation.
Table 55. UMSEL Bit Settings
UMSEL
Mode
0
1
Asynchronous Operation
Synchronous Operation
153
2486M–AVR–12/03
ATMEL [ ATMEL ]
