AT90SCR100 datasheet(260/433 Pages) ATMEL

260 / 433 page

260

TPR0327AY–SMS–30Jan09

AT90SCR100

can be used to check that the Transmitter has completed all transfers, and the RXC0 Flag can

be used to check that there are no unread data in the receive buffer. Note that the TXC0 Flag

must be cleared before each transmission (before UDR0 is written) if it is used for this purpose.

The following simple USART initialization code examples show one assembly and one C func-

tion that are equal in functionality. The examples assume polling (no interrupts enabled). The

baud rate is given as a function parameter. For the assembly code, the baud rate parameter is

assumed to be stored in the r17:r16 registers.

19.6

Data Transfer

Using the USART in MSPI mode requires the Transmitter to be enabled, i.e. the TXEN0 bit in

the UCSR0B register is set to one. When the Transmitter is enabled, the normal port operation

of the TxD0 pin is overridden and given the function as the Transmitter's serial output. Enabling

Assembly Code Example

USART_Init:

clr

r18

out

UBRR0H,r18

out

UBRR0L,r18

; Setting the XCK0 port pin as output, enables master mode.

sbi

XCK0_DDR, XCK0

; Set MSPI mode of operation and SPI data mode 0.

ldi

r18, (1<<UMSEL01)|(1<<UMSEL00)|(0<<UCPHA0)|(0<<UCPOL0)

out

UCSR0C,r18

; Enable receiver and transmitter.

ldi

r18, (1<<RXEN0)|(1<<TXEN0)

out

UCSR0B,r18

; Set baud rate.

; IMPORTANT: The Baud Rate must be set after the transmitter is enabled!

out

UBRR0H, r17

out

UBRR0L, r18

ret

C Code Example

void

USART_Init( unsigned int baud )

{

UBRR0 = 0;

/* Setting the XCK0 port pin as output, enables master mode. */

XCK0_DDR |= (1<<XCK0);

/* Set MSPI mode of operation and SPI data mode 0. */

UCSR0C = (1<<UMSEL01)|(1<<UMSEL00)|(0<<UCPHA0)|(0<<UCPOL0);

/* Enable receiver and transmitter. */

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

/* Set baud rate. */

/* IMPORTANT: The Baud Rate must be set after the transmitter is enabled

UBRR0 = baud;

}

AT90SCR100 Datasheet(PDF) 260 Page - ATMEL Corporation

AT90SCR100 Datasheet(HTML) 260 Page - ATMEL Corporation

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