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ATmega161(L)
1228B–09/01
UART0 and UART1 High Byte
Baud Rate Register UBRRHI
The UART baud register is a 12-bit register. The four most significant bits are located in
a separate register, UBRRHI. Note that both UART0 and UART1 share this register. Bit
7 to bit 4 of UBRRHI contain the four most significant bits of the UART1 baud register.
Bit 3 to bit 0 contain the four most significant bits of the UART0 baud register.
UART0 Baud Rate Register
Low Byte – UBRR0
UART1 Baud Rate Register
Low Byte – UBRR1
UBRRn stores the eight least significant bits of the UART baud rate register.
Bit
7
6
5
4
3
2
1
0
$20 ($40)
MSB1
LSB1
MSB0
LSB0
UBRRHI
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
$09 ($29)
MSB
LSB
UBRR0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
$00 ($20)
MSB
LSB
UBRR1
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0