# Write Access

When doing a write access of this I/O location, the high bit of the value written, the USART Register Select (URSEL) bit, controls which one of the two registers that will be written. If URSEL is zero during a write operation, the UBRRH value will be updated. If URSEL is one, the UCSRC setting will be updated.

The following code examples show how to access the two registers.

## Assembly Code Example(1)

:.
; Set UBRRH to 2
ldi r16,0x02
out UBRRH,r16
:.
; Set the USBS and the UCSZ1 bit to one, and
; the remaining bits to zero.
ldi r16,(1<<URSEL) | (1<<USBS) | (1<<UCSZ1)
out UCSRC,r16
:.
:.
/* Set UBRRH to 2 */
UBRRH = 0x02;
:.
/* Set the USBS and the UCSZ1 bit to one, and */
/* the remaining bits to zero. */
UCSRC = (1<<URSEL) | (1<<USBS) | (1<<UCSZ1);
:.
Note: 1. See About Code Examples.

As the code examples illustrate, write accesses of the two registers are relatively unaffected of the sharing of I/O location.