ATmega88 @ 8MHz SPI-Slave - Daten am MOSI per Interrupt Anforderung empfangen und am PORTD ausgeben

spi-receive-02.c

/*
* spi_receive_02.c
* SPI-Slave - Daten am MOSI per Interrupt Anforderung empfangen und am PORTD ausgeben
* Controller: ATmega88 @ 8MHz
*/
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
 
void SPI_Slave_Init(void)
{
    SPCR &= ~(1<<MSTR);               // Controller = Slave
    SPCR &= ~(1<<CPOL);               // CLK positiv phase
    SPCR |= (1<<CPHA);                // Sampling data @ rising edge
    SPCR |= ((1<<SPE)|(1<<SPIE));   // Enable SPI && interrupt enable bit
    DDRB |= (1<<PB4);             // Set MISO output
    DDRB &= ~(1<<PB3);                // Set MOSI input
    DDRB &= ~(1<<PB5);                // Set SCK input
    DDRB &= ~(1<<PB2);                // Set SS input
}
 
uint8_t SPI_Slave_Receive(void)
{
    while (!(SPSR & (1<<SPIF)));  // Wait for transmission complete
    return SPDR;                    // return spi data register
}
 
int main(void)
{
    DDRD = 0xFF;
    SPI_Slave_Init();               // Init SPI Interface as Slave
     
    sei();                          // enable Interrupts
     
    while(1)
    {
    }
}
 
/**** Interrupt Service Routine (SPI serial transfer complete) ****/
ISR(SPI_STC_vect)
{
    PORTD = SPI_Slave_Receive();    // Daten abholen und am PORTD ausgeben
}