Rainbow-electronics ATmega8515L Instrukcja Użytkownika Pobierz pdf (Strona 126)

126

ATmega8515(L)

2512A–AVR–04/02

The following codeexamplesshowhow to initializethe SPI as a Slave andhow to per-

formasimple reception.

Note: 1. Theexample codeassumes that the part specificheaderfileis included.

Assembly Code Example

(1)

SPI_SlaveInit:

; Set MISO output, all others input

ldi r17,(1<<DD_MISO)

out DDR_SPI,r17

; Enable SPI

ldi r17,(1<<SPE)

out SPCR,r17

ret

SPI_SlaveReceive:

; Wait for reception complete

sbis SPSR,SPIF

rjmp SPI_SlaveReceive

; Read received data and return

in r16,SPDR

ret

CCode 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;

}

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Rainbow-electronics ATmega8515L Instrukcja Użytkownika Strona 126