forked from interactive-matter/Blinken-Button
/
spi.c
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/
spi.c
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/**
* SPI support
*/
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
#include "display.h"
#define SS PB2
#define MOSI PB3
#define MISO PB4
#define SCK PB5
// Sprite buffer
uint8_t sprite[8] = {0, 0, 0, 0, 0, 0, 0, 0};
uint8_t i = 0;
/**
* Initialize SPI in slave mode
*/
void spi_init(void)
{
volatile char IOReg;
// Set MISO output
DDRB |= (1<<MISO);
// Enable SPI (slave) and SPI interrupts
SPCR = (1<<SPE) | (1<<SPIE);
// Clear SPIF bit in SPSR
IOReg = SPSR;
IOReg = SPDR;
}
/**
* SPI interrupt routine
*/
ISR(SPI_STC_vect)
{
// Save sprite into buffer
sprite[i++] = SPDR;
if (i == 8) {
// Sprite completed
i = 0;
display_load_sprite(sprite);
display_advance_buffer();
}
}