/*
 * Konfiguration vom AD9833
 * 
 */

#include <avr/io.h>
#include <avr/sleep.h>

// ftw = freq * ACCU_SIZE / F_DDS
//     = freq * 2^28 / 25e6 Hz
//     = freq * 10.73741824

// Manuelle Berechnung fuer 5845000 Hz
// FTW frequency tuning word

#define FTW 62760209
#define FA (0x4000 | (FTW & 0x3FFF) )           // LSB fuer F0
#define FB (0x4000 | ((FTW>>14) & 0x3FFF) )     // MSB fuer F0


// PINs

#define FSYNC_LOW  PORTB &= ~(1<<PB0)
#define FSYNC_HIGH PORTB |=  (1<<PB0)
#define CLK_LOW    PORTB &= ~(1<<PB1)
#define CLK_HIGH   PORTB |=  (1<<PB1)
#define DATA_LOW   PORTB &= ~(1<<PB2)
#define DATA_HIGH  PORTB |=  (1<<PB2)

void write_reg(uint16_t data) {
  uint8_t i;

  FSYNC_LOW;
  for (i=0; i<16; i++) {
    if (data & 0x8000) DATA_HIGH; else DATA_LOW;
    CLK_LOW;
    CLK_HIGH;
    data <<= 1;
  }
  FSYNC_HIGH;
}

int main(void) {

    DDRB  = (1<<PB2) | (1<<PB1) | (1<<PB0);
    PORTB = 0xFF;

    write_reg(0x2100);    // Reset active, 28 bit mode
    write_reg(FA);
    write_reg(FB);
    write_reg(0x2000);    // Reset inactive, 28 bit mode, select F0
    
    set_sleep_mode(SLEEP_MODE_PWR_DOWN);
    sleep_mode();
}