ATmega169P datasheet(182/393 Pages) ATMEL

182 / 393 page

182

8018N–AVR–08/09

ATmega169P

Note:

1. ”About Code Examples” on page 10

The receive function example reads all the I/O Registers into the Register File before any com-

putation is done. This gives an optimal receive buffer utilization since the buffer location read will

be free to accept new data as early as possible.

Assembly Code Example(1)

USART_Receive:

; Wait for data to be received

sbis

UCSR0A, RXC0

rjmp

USART_Receive

; Get status and 9th bit, then data from buffer

r18, UCSR0A

r17, UCSR0B

r16, UDR0

; If error, return -1

andi

r18,(1<<FE0)|(1<<DOR0)|(1<<UPE0)

breq

USART_ReceiveNoError

ldi

r17, HIGH(-1)

ldi

r16, LOW(-1)

USART_ReceiveNoError:

; Filter the 9th bit, then return

lsr

r17

andi

r17, 0x01

ret

C Code Example(1)

unsigned int

USART_Receive( void )

{

unsigned char

status, resh, resl;

/* Wait for data to be received */

while

( !(UCSRnA & (1<<RXCn)) )

;

/* Get status and 9th bit, then data */

/* from buffer */

status = UCSR0A;

resh = UCSR0B;

resl = UDR0;

/* If error, return -1 */

( status & (1<<FE0)|(1<<DOR0)|(1<<UPE0) )

return

-1;

/* Filter the 9th bit, then return */

resh = (resh >> 1) & 0x01;

return

((resh << 8) | resl);

}

ATmega169P Datasheet(PDF) 182 Page - ATMEL Corporation

ATmega169P Datasheet(HTML) 182 Page - ATMEL Corporation

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