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ATmega165A/PA/325A/PA/3250A/PA/645A/P/6450A/P [DATASHEET]
8285E–AVR–02/2013
Note:
More advanced initialization routines can be made that include frame format as parameters, disable interrupts and
so on. However, many applications use a fixed setting of the baud and control registers, and for these types of
applications the initialization code can be placed directly in the main routine, or be combined with initialization code
for other I/O modules.
Assembly code example
(1)USART_Init:
; Set baud rate
sts
UBRR0H, r17
sts
UBRR0L, r16
; Enable receiver and transmitter
ldi
r16, (1<<RXEN0)|(1<<TXEN0)
sts
UCSR0B,r16
; Set frame format: 8data, 2stop bit
ldi
r16, (1<<USBS0)|(3<<UCSZ00)
sts
UCSR0C,r16
ret
C code example
#define FOSC 1843200// Clock Speed
#define BAUD 9600
#define MYUBRR FOSC/16/BAUD-1
void
main( void )
{
...
USART_Init ( MYUBRR );
...
}
void
USART_Init( unsigned int ubrr)
{
/* Set baud rate */
UBRRH0 = (unsigned char)(ubrr>>8);
UBRRL0 = (unsigned char)ubrr;
/* Enable receiver and transmitter */
UCSR0B = (1<<RXEN0)|(1<<TXEN0);
/* Set frame format: 8data, 2stop bit */
UCSRnC = (1<<USBS0)|(3<<UCSZ00);
}