File content as of revision 0:4a6c8e7e8ea7:

#include "mbed.h"

DigitalOut LED_3(LED3);

/******
PIN + SPI CONFIG
******/

SPI SPI_AFE_ADC_AND_DDS(p5, p6, p7); //SPI0: MOSI, MISO, SCLK
DigitalOut ADC_nCS(p8);  //ADC_!CS
DigitalOut DDS_nCS(p15);   //DDS_!CS

SPI SPI_CUR_ADC(p11, p12, p13); //SPI1 - see page 601 of 947
DigitalOut CUR_nCS(p14);   //DDS_!CS

//  These pins control the Phase register and the Frequency register, IF THE DDS IS CONFIGURED TO BE CONTROLLED BY THE PINS,
//BY DEFAULT, AND HOW I HAVE IT CONFIGURED IS TO NOT USE THESE PINS, REPEAT, it does NOT USE THE PINS, instead uses the SPI bus.
//  By toggling them after config, you can create PSK, FSK, BPSK...
DigitalOut DDS_PSEL(p16);    
DigitalOut DDS_FSEL(p17);  

DigitalOut SQUARE(p18); //currently does nothing, =1 closes switch to SQUARE path that is not populated
DigitalOut DDS(p19); //if=1, DDS output connected to TX_PORT
DigitalOut AFE(p20); //if=1, Electrode routed to Amplification Path


#define SSP_SR_TFE (1<<0)
#define SSP_SR_TNF (1<<1)
#define SSP_SR_RFE (1<<2)
#define SSP_SR_RFF (1<<3)
#define SSP_SR_BSY (1<<4)

void writeReg(uint16_t val){
    __disable_irq();

    DDS_nCS = 0;
    //DDS_nCS0;
    
    while ( !(LPC_SSP0->SR & SSP_SR_TNF) ); //while ssp is not writable
    LPC_SSP0->DR = val;                //write this out 
    while ( (LPC_SSP0->SR & SSP_SR_BSY) ); //wait until transmission is over to pull ncs up
    
    DDS_nCS = 1;
    //DDS_nCS1;
    
    __enable_irq();
}

/******************
DDS Library ported from https://github.com/arachnidlabs/ad983x/blob/master/ad983x.cpp
******************/
#define REG_OPBITEN 0x0020
#define REG_SIGNPIB 0x0010
#define REG_DIV2    0x0008
#define REG_MODE    0x0002
#define SIGN_OUTPUT_MASK (REG_OPBITEN | REG_SIGNPIB | REG_DIV2 | REG_MODE)

uint16_t m_reg;

enum SignOutput {
  SIGN_OUTPUT_NONE        = 0x0000,
  SIGN_OUTPUT_MSB         = 0x0028,
  SIGN_OUTPUT_MSB_2       = 0x0020,
  SIGN_OUTPUT_COMPARATOR  = 0x0038,
};

void setSignOutput(SignOutput out) {
  m_reg = (m_reg & ~SIGN_OUTPUT_MASK) | out;
  writeReg(m_reg);
}

enum OutputMode {
  OUTPUT_MODE_SINE        = 0x0000,
  OUTPUT_MODE_TRIANGLE    = 0x0002,
};

void setOutputMode(OutputMode out) {
  if(out == OUTPUT_MODE_TRIANGLE) {
    m_reg = (m_reg & ~SIGN_OUTPUT_MASK) | out;
  } else {
    m_reg &= ~REG_MODE;
  }
  writeReg(m_reg);
}

#define REG_FREQ1   0x8000
#define REG_FREQ0   0x4000
void setFrequencyWord(bool reg, uint32_t frequency) {
  writeReg(0x2000);
  writeReg((reg?REG_FREQ1:REG_FREQ0) | (frequency & 0x3FFF));
  writeReg((reg?REG_FREQ1:REG_FREQ0) | ((frequency >> 14) & 0x3FFF));
}

#define REG_PHASE0  0xC000
#define REG_PHASE1  0xE000
void setPhaseWord(bool reg, uint32_t phase) {
  writeReg((reg?REG_PHASE1:REG_PHASE0) | (phase & 0x0FFF));
}

#define REG_FSEL    0x0800
void selectFrequency(bool reg) {
  if(reg) {
    m_reg |= REG_FSEL;
  } else {
    m_reg &= ~REG_FSEL;
  }
  writeReg(m_reg);
}

#define REG_PSEL    0x0400
void selectPhase(bool reg) {
  if(reg) {
    m_reg |= REG_PSEL;
  } else {
    m_reg &= ~REG_PSEL;
  }
  writeReg(m_reg);
}

#define REG_RESET   0x0100
void reset(bool in_reset) {
  if(in_reset) {
    m_reg |= REG_RESET;
  } else {
    m_reg &= ~REG_RESET;
  }
  writeReg(m_reg); //writes 16 bits over SPI
}

void begin(){
    reset(true);
    writeReg(m_reg);
    // Initialize frequency and phase registers to 0
    setFrequencyWord(0, 0);
    setFrequencyWord(1, 0);
    setPhaseWord(0, 0);
    setPhaseWord(1, 0);
    reset(false);
}

/*******************
MAIN
*******************/
int main() {
    //init pins
    DDS_PSEL = 0;
    DDS_FSEL = 0;
    SQUARE = 0;
    DDS = 0;
    AFE = 0;
    LED_3 = 1;
    
    //nCS lines
    DDS_nCS = 1;
    CUR_nCS = 1;
    ADC_nCS = 1;
    
    //init spi
    SPI_AFE_ADC_AND_DDS.format(16,2);
    SPI_AFE_ADC_AND_DDS.frequency(33000000);
    
    //make sure SPI is setup to mode 2, MSB first
    //init DDS
    begin();
    //output calculation
    //fOut = fMCLK / 2^28 * FREQREG = 16e6 / 2^28 * FREQREG
    //FREQREG = fOut * 2^28 / 16e6 = fOut * 16.777216
    setFrequencyWord(0, 134217728);
    selectFrequency(0);
    
    setSignOutput(SIGN_OUTPUT_MSB);
    //open the DDS output
    SQUARE = 1;
    
    
}