ATTINY20_13 Datasheet, PDF (129/220 Pages) ATMEL Corporation – 8-bit AVR Microcntroller with 2K Bytes In-System Programmable Flash

C Code Example
void SPI_MasterInit(void)
{
/* Set MOSI and SCK output, all others input */
DDR_SPI = (1<<DD_MOSI)|(1<<DD_SCK);
/* Enable SPI, Master, set clock rate fck/16 */
SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR0);
}
void SPI_MasterTransmit(char cData)
{
/* Start transmission */
SPDR = cData;
/* Wait for transmission complete */
while(!(SPSR & (1<<SPIF)))
;
}
Note: See ”Code Examples” on page 7.
The following code examples show how to initialize the SPI as a Slave and how to perform a simple reception.
Assembly Code Example
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
in
r16, SPSR
sbrs
r16, SPIF
rjmp
SPI_SlaveReceive
; Read received data and return
in
r16,SPDR
ret
ATtiny20 [DATASHEET]
8235E–AVR–03/2013
129