#include <avr/io.h>

#if defined(__AVR_ATmega32__)
#elif defined(__AVR_AT90S8515__)
#define SS PB4
#define MOSI PB5
#define SCK PB7
#elif defined(__AVR_ATmega8__)
#define SS PB2
#define MOSI PB3
#define SCK PB5
#elif defined(__AVR_ATmega48__)
#define SS PB2
#define MOSI PB3
#define SCK PB5
#endif

#include "led_driver.h"

void led_init(void)
{
    //CPOL=0,CPHA=0 -> Sample on rising edge, standard phase.
    #if defined(__AVR_ATmega32__)
    SPCR=0x51;//Enable SPI, MSB first, master mode, 16 MHz/16 = 1 MHz clock.
    #else
    SPCR=0x50;//Enable SPI, MSB first, master mode, 4 MHz/4 = 1 MHz clock.
    #endif
    
    //FIXME Flicker disappears when these lines are removed!
    DDRB|=1<<SS;//SS (LE).
    DDRB|=1<<MOSI;//MOSI.
    DDRB|=1<<SCK;//SCK.
    PORTB|=1<<SS;//Data latched on LE low (keep high).
}

void led_set(unsigned int on)
{
    unsigned char temp;

    PORTB|=1<<SS;//Data register transparent.

    SPDR=(on>>8)&0xFF;//MSB
    while(!(SPSR&0x80));//Wait for transfer complete.
    temp=SPDR;
    
    SPDR=on&0xFF;//LSB
    while(!(SPSR&0x80));//Wait for transfer complete.
    temp=SPDR;//Access SPDR to clear second SPIF flag.

    PORTB&=~(1<<SS);//Latch register.
}