24.12.5 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 |
| Property: | - |
| 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.