DDS Function Generator

/*  Sketch for e-Gizmo DDS Function Generated Breakout Board */


/* Pin assignment
Change accordingly if you have your own pin allotment preference
*/

const int latchPin = 10;  // Connected to Function Gen SYNC pin
const int clockPin = 13;  // Connected to Function Gen CLK pin
const int dataPin = 11;   // Connected to Function Gen DATA pin

/* Waveform Output Control word */
const int SINE=0x2008;
const int TRIANGLE= 0x200A;
const int SQUARE = 0x2028;

void setup() {
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
}

void loop() {
  int i;
  
  /* Demonstration Routine */
  
  // display sine, triangle, and square 5x @ 1khz
  for(i=1;i<5;i++){
    Set_Gen(SINE,1000);
    delay(1000);
    Set_Gen(TRIANGLE,1000);
    delay(1000);
    Set_Gen(SQUARE,1000);
    delay(1000);
  }
  
    // display sine, triangle, and square 5x @ 100khz
  for(i=1;i<5;i++){
    Set_Gen(SINE,100000);
    delay(1000);
    Set_Gen(TRIANGLE,100000);
    delay(1000);
    Set_Gen(SQUARE,100000);
    delay(1000);
  }
  
  
  
}

/* ----- DDS Core Functions ---- */


/* Emulate 16-bit SPI transfer */
void SPI16(int spidata){
  int spidatah;
  int spidatal;
  
  spidatah= spidata>>8;
  spidatal= spidata & 0xFF;
  
    digitalWrite(clockPin, HIGH);
    digitalWrite(latchPin, LOW);
    shiftOut(dataPin, clockPin, MSBFIRST, spidatah); 
    digitalWrite(clockPin, HIGH);
    shiftOut(dataPin, clockPin, MSBFIRST, spidatal); 
    digitalWrite(clockPin, HIGH);
    digitalWrite(latchPin, HIGH);
}    

/* Set up Function gen to generate waveform at desired frequency */

void Set_Gen(int waveform,float frequency){
  long int freqdiv;
  int freqdivh;
  int freqdivl;
  
  // compute for 28 bit frequency divider parameters
  freqdiv=frequency*53.6870912;
  freqdivh=freqdiv>>14;    // upper 14 bits extracted
  freqdivh &= 0x3FFF;
  freqdivl=freqdiv & 0x3FFF; // lower 14 bits extracted
  freqdivh |= 0x4000;      // control bits added
  freqdivl |= 0x4000;
  
  SPI16(waveform);        // set waveform
  SPI16(freqdivl);        // set frequency
  SPI16(freqdivh);
}