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.
Bit15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 |
UBRRn[11:8] | |||||||
Access | R/W | R/W | R/W | R/W | |||
Reset | 0 | 0 | 0 | 0 | |||
Bit7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
UBRRn[7:0] | |||||||
AccessR/W | R/W | R/W | R/W | R/W | R/W | R/W | R/W |
Reset0 | 0 | 0 | 0 | 0 | 0 | 0 | 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.