AT90SCR100 datasheet(241/433 Pages) ATMEL

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TPR0327AY–SMS–30Jan09

AT90SCR100

bits of the data read from the UDR0 will be masked to zero. The USART has to be initialized

before the function can be used.

Note:

1. See “About Code Examples” on page 11.

The function simply waits for data to be present in the receive buffer by checking the RXC0 Flag,

before reading the buffer and returning the value.

18.8.2

Receiving Frames with 9 Data Bits

If 9-bit characters are used (UCSZ0=7) the ninth bit must be read from the RXB80 bit in

UCSR0B before reading the low bits from the UDRn. This rule applies to the FE0, DOR0 and

UPE0 Status Flags as well. Read status from UCSR0A, then data from UDR0. Reading the

UDR0 I/O location will change the state of the receive buffer FIFO and consequently the TXB80,

FE0, DOR0 and UPE0 bits, which all are stored in the FIFO, will change.

The following code example shows a simple USART receive function that handles both nine bit

characters and the status bits.

Assembly Code Example(1)

USART_Receive:

; Wait for data to be received

sbis

UCSR0A, RXC0

rjmp

USART_Receive

; Get and return received data from buffer

r16, UDR0

ret

C Code Example(1)

unsigned char

USART_Receive( void )

{

/* Wait for data to be received */

while

( !(UCSR0A & (1<<RXC0)) )

;

/* Get and return received data from buffer */

return

UDR0;

}

AT90SCR100 Datasheet(PDF) 241 Page - ATMEL Corporation