Datasheet

24.12.5 USART Baud Rate n Register Low and High byte

Name: UBRR

Offset: 0xC4 + n*0x08 [n=0..1]

Reset: 0x00

Property: -

The UBRRnL and UBRRnH register pair represents the 16-bit value, UBRRn (n=0,1). The low byte [7:0]

(suffix L) is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset

+ 0x01. For more details on reading and writing 16-bit registers, refer to Accessing 16-bit Timer/Counter

Registers.

Bit 15 14 13 12 11 10 9 8

UBRRn[11:8]

Access

R/W R/W R/W R/W

Reset 0 0 0 0

Bit 7 6 5 4 3 2 1 0

UBRRn[7:0]

Access

R/W R/W R/W R/W R/W R/W R/W R/W

Reset 0 0 0 0 0 0 0 0

Bits 11:0 – UBRRn[11:0] USART Baud Rate

This is a 12-bit register which contains the USART baud rate. The UBRRnH contains the four most

significant bits and the UBRRnL contains the eight least significant bits of the USART n baud rate.

Ongoing transmissions by the Transmitter and Receiver will be corrupted if the baud rate is changed.

Writing UBRRnL will trigger an immediate update of the baud rate prescaler.