#include <limits.h>

#ifndef PIN_BCK
#define PIN_BCK   22
#endif

#ifndef PIN_WS
#define PIN_WS    23
#endif

#ifndef PIN_DIN
#define PIN_DIN   24
#endif

#define NOP __asm__ __volatile__ ("nop\n\t")

void writeDACChannel(short waveData)
{
  unsigned char pos = 16;

  // Send data into PT8211 in least significant bit justified (LSBJ) format.
  while(pos > 0)
  {
    pos--;
    digitalWrite(PIN_BCK, LOW);
    // Write next bit in stream into DIN.
    digitalWrite(PIN_DIN, (waveData & (1 << pos)) ? HIGH : LOW);
    NOP;
    // Toggle BCK.
    digitalWrite(PIN_BCK, HIGH);
    NOP;
  }
}

void writeDAC(short waveData)
{
  digitalWrite(PIN_WS, LOW);
  digitalWrite(PIN_BCK, LOW);
  // Write data into right channel of DAC.
  writeDACChannel(waveData);
  digitalWrite(PIN_WS, HIGH);
  // Write data into left channel of DAC.
  writeDACChannel(waveData);
}

void setup()
{
  pinMode(PIN_BCK, OUTPUT);
  pinMode(PIN_WS, OUTPUT);
  pinMode(PIN_DIN, OUTPUT);
}

void loop()
{
  short pos = 0;
  while(pos < 360)
  {
    pos += 5;
    if(pos > 360)
    {
      pos = 0;
      continue;
    }

    writeDAC(sin(radians(pos)) * SHRT_MAX);
  }
}