8-bit AVR Microcontroller

USART Baud Rate 0 Register Low and High byte

The UBRR0L and UBRR0H register pair represents the 16-bit value, UBRR0.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 Registers.

Name:
UBRR0L and UBRR0H
Offset:
0x09
Reset:
0x00
Access:
-
Bit15141312111098
UBRR0[11:8]
AccessR/WR/WR/WR/W
Reset0000
Bit76543210
UBRR0[7:0]
AccessR/WR/WR/WR/WR/WR/WR/WR/W
Reset00000000

Bits 11:0 – UBRR0[11:0]: USART Baud Rate

USART Baud Rate

This is a 12-bit register which contains the USART baud rate. The UBRR0H contains the four most significant bits and the UBRR0L contains the eight least significant bits of the USART 0 baud rate. Ongoing transmissions by the Transmitter and Receiver will be corrupted if the baud rate is changed. Writing UBRR0L will trigger an immediate update of the baud rate prescaler.