sine_test.ino

// http://arduino.cc/forum/index.php/topic,45579.0.html
#include <SPI.h>

int CS_pin = 9;
int DREQ_pin = 3;
byte received;

void setup()
{
    Serial.begin(9600);
  pinMode(CS_pin, OUTPUT);
  pinMode(DREQ_pin, INPUT);

  SPI.begin();
  SPI.setBitOrder(MSBFIRST);

  //CPOL = 0, CPHA = 1
  //see en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus#Mode_Numbers
  //and decoder chip datasheet
  SPI.setDataMode(SPI_MODE1);
  //max SDI clock freq = CLKI/7 and (datasheet) CLKI = 36.864, hence max clock = 5MHz
  //SPI clock arduino = 16MHz. 16/ 4 = 4MHz -- ok!
  SPI.setClockDivider(SPI_CLOCK_DIV4);

}

void loop()
{
  digitalWrite(CS_pin, HIGH);
  delay(5);

  // CHIP Write
  // sets sci_mode register, SM_SDINEW, SM_SDISHARE, SM_TESTS.  pg 25, 26
  byte aux;
  digitalWrite(CS_pin, LOW);
  delay(1);
  SPI.transfer(0x02);  //write command
  SPI.transfer(0x00); //SDI_MODE register
  //extract and send higher byte of data
  aux = 0x0c20 >> 8;
  SPI.transfer(aux);
  //extract and send lower byte of data
  aux = 0x0c20 & 0b11111111;
  SPI.transfer(aux);
  //wait for the chip to finish executing command
  while (!DREQ_pin){};
  digitalWrite(CS_pin, HIGH);
  delay(1);

  Serial.println("starting sine test");
  // Start SINE test
  digitalWrite(CS_pin, HIGH);
  delay(1);
  SPI.transfer(0x53);
  SPI.transfer(0xEF);
  SPI.transfer(0x6E);
  SPI.transfer(0xAA); // 44100 Hz test tone frequency (pg 35)
  SPI.transfer(0);
  SPI.transfer(0);
  SPI.transfer(0);
  SPI.transfer(0);

  delay(200);

  // EXIT SINE test
  digitalWrite(CS_pin, HIGH);
  delay(1);
  SPI.transfer(0x45);
  SPI.transfer(0x78);
  SPI.transfer(0x69);
  SPI.transfer(0x74);
  SPI.transfer(0);
  SPI.transfer(0);
  SPI.transfer(0);
  SPI.transfer(0);

  Serial.println("exited sine test");

  delay(200);
}