ATMEGA48 datasheet(178/374 Pages) ATMEL

178 / 374 page

178

2545J–AVR–12/06

ATmega48/88/168

For the assembly code, the baud rate parameter is assumed to be stored in the r17:r16

Registers.

Note:

1. See ”About Code Examples” on page 8.

More advanced initialization routines can be made that include frame format as parameters, dis-

able 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

out

UBRRnH, r17

out

UBRRnL, r16

; Enable receiver and transmitter

ldi

r16, (1<<RXENn)|(1<<TXENn)

out

UCSRnB,r16

; Set frame format: 8data, 2stop bit

ldi

r16, (1<<USBSn)|(3<<UCSZn0)

out

UCSRnC,r16

ret

C Code Example

(1)

#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 */

UBRR0H = (unsigned char)(ubrr>>8);

UBRR0L = (unsigned char)ubrr;

Enable receiver and transmitter */

UCSR0B = (1<<RXEN0)|(1<<TXEN0);

/* Set frame format: 8data, 2stop bit */

UCSR0C = (1<<USBS0)|(3<<UCSZ00);

}

ATMEGA48 Datasheet(PDF) 178 Page - ATMEL Corporation

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