USART Baud Rate n Register Low and High byte

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.

Name:
UBRR
Offset:
0xC4 + n*0x08 [n=0..1]
Reset:
0x00
Access:
-
Bit15141312111098
UBRRn[11:8]
AccessR/WR/WR/WR/W
Reset0000
Bit76543210
UBRRn[7:0]
AccessR/WR/WR/WR/WR/WR/WR/WR/W
Reset00000000

Bits 11:0 – UBRRn: USART Baud Rate

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.