Datasheet

241
ATmega640/1280/1281/2560/2561
2549K–AVR–01/07
Note: 1. See “About Code Examples” on page 9.
Transmitter and Receiver
Flags and Interrupts
The RXCn, TXCn, and UDREn flags and corresponding interrupts in USART in MSPIM
mode are identical in function to the normal USART operation. However, the receiver
error status flags (FE, DOR, and PE) are not in use and is always read as zero.
Disabling the Transmitter or
Receiver
The disabling of the transmitter or receiver in USART in MSPIM mode is identical in
function to the normal USART operation.
Assembly Code Example
(1)
USART_MSPIM_Transfer:
; Wait for empty transmit buffer
sbis UCSRnA, UDREn
rjmp USART_MSPIM_Transfer
; Put data (r16) into buffer, sends the data
out UDRn,r16
; Wait for data to be received
USART_MSPIM_Wait_RXCn:
sbis UCSRnA, RXCn
rjmp USART_MSPIM_Wait_RXCn
; Get and return received data from buffer
in r16, UDRn
ret
C Code Example
(1)
unsigned char USART_Receive( void )
{
/* Wait for empty transmit buffer */
while ( !( UCSRnA & (1<<UDREn)) );
/* Put data into buffer, sends the data */
UDRn = data;
/* Wait for data to be received */
while ( !(UCSRnA & (1<<RXCn)) );
/* Get and return received data from buffer */
return UDRn;
}