ATmega16A datasheet(153/352 Pages) ATMEL

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153

8154B–AVR–07/09

ATmega16A

Note:

1. See “About Code Examples” on page 7.

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.

19.6

Data Transmission – The USART Transmitter

The USART Transmitter is enabled by setting the Transmit Enable (TXEN) bit in the UCSRB

den by the USART and given the function as the transmitter’s serial output. The baud rate, mode

of operation and frame format must be set up once before doing any transmissions. If synchro-

nous operation is used, the clock on the XCK pin will be overridden and used as transmission

clock.

Assembly Code Example

(1)

USART_Init:

; Set baud rate

out

UBRRH, r17

out

UBRRL, r16

; Enable receiver and transmitter

ldi

r16, (1<<RXEN)|(1<<TXEN)

out

UCSRB,r16

; Set frame format: 8data, 2stop bit

ldi

r16, (1<<URSEL)|(1<<USBS)|(3<<UCSZ0)

out

UCSRC,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 */

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

UBRRL = (unsigned char)ubrr;

/* Enable receiver and transmitter */

UCSRB = (1<<RXEN)|(1<<TXEN);

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

UCSRC = (1<<URSEL)|(1<<USBS)|(3<<UCSZ0);

}

ATmega16A Datasheet(PDF) 153 Page - ATMEL Corporation

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