ATmega640/1280/1281/2560/2561
The following code examples show how to initialize the SPI as a Slave and how to per-
form a simple reception.
Assembly Code Example(1)
SPI_SlaveInit:
; Set MISO output, all others input
ldi
out
r17,(1<<DD_MISO)
DDR_SPI,r17
; Enable SPI
ldi
out
ret
r17,(1<<SPE)
SPCR,r17
SPI_SlaveReceive:
; Wait for reception complete
sbis SPSR,SPIF
rjmp SPI_SlaveReceive
; Read received data and return
in
r16,SPDR
ret
C Code Example(1)
void SPI_SlaveInit(void)
{
/* Set MISO output, all others input */
DDR_SPI = (1<<DD_MISO);
/* Enable SPI */
SPCR = (1<<SPE);
}
char SPI_SlaveReceive(void)
{
/* Wait for reception complete */
while(!(SPSR & (1<<SPIF)))
;
/* Return Data Register */
return SPDR;
}
Note:
1. See “About Code Examples” on page 8.
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2549A–AVR–03/05
ATMEL [ ATMEL ]
