File content as of revision 16:07d0e43c2d12:

/**
* @file LDC1101.cpp
* @brief this C++ file contains all required
* functions to interface with Texas
* Instruments' LDC1101.
*
* @author Victor Sluiter
*
* @date 2015-12-09
*/

#include "LDC1101.h"

 
LDC1101::LDC1101(PinName mosi, PinName miso, PinName sck, PinName cs, float capacitor, float f_external, PinName clock_out) : _spiport(mosi,miso,sck, NC), _cs_pin(cs), _clock(clock_out,1)
{

    cap = capacitor;
    _spiport.format(8,3);
    _spiport.frequency(1E6);
    setFrequency(f_external);
    
    // ---CSB must go low before accessing first address???
    _cs_pin.write(1);
    wait_us(100);
    
    init();
}

void LDC1101::init()
{
    // configuration
    mode(LDC_MODE_STANDBY);     // 0x01 naar 0x0B  
    
    wait(0.1);
    wait_us(10);

    setResponseTime(LDC_RESPONSE_6144);

    // L-Only Measurement
    writeSPIregister(0x05, 0x03);   // ALT_CONFIG:  clock config >> we get 0x00 if this line is disabled and the cable is reconnected 
    writeSPIregister(0x0C, 0x01);   // D_CONF:      Register 0x0C enables a function that can improve L measurements while disabling RP measurements 

    // High Resolution Reference Count
    // LHR_COUNT_LSB:   0xff naar 0x30 ???
    // LHR_COUNT_MSB:   0xff naar 0x31 ???

    // Start measuring
    mode(LDC_MODE_ACTIVE);      // 0x00 naar 0x0B
}

void LDC1101::setResponseTime(LDC_RESPONSE responsetime)
{
    _responsetime = responsetime;
    writeSPIregister(0x04, responsetime);
}

void LDC1101::setFrequency(float frequency)
{
    _frequency = frequency;
    _clock.period(1.0/frequency);
    _clock.pulsewidth(0.5/frequency);
}

float LDC1101::getInductance()
{
    uint16_t resp[] = {0,0,192, 384, 768, 1536, 3072, 6144};
    _raw_l = readRawCounts();
    
    // f_CLKIN * RESP_TIME
    // -------------------
    //      3 * L_DATA
    _fsensor = (_frequency/(_raw_l*3.0))*resp[(uint8_t)(_responsetime)];
    
    //            1
    // ---------------------        --> p. 31
    // C * (2*PI*f_sensor)^2
    return 1./(cap*pow(2*PI*_fsensor,2));
};


uint32_t LDC1101::readRawCounts(void)
{
    uint8_t val[5];
    
    // 0x38 + 0x39 + 0x3A
    readSPI(val, 0x38, 5);
    uint32_t combinedbytes = (val[4]<<16)| (val[3]<<8) | val[2];  // combine the content of the 3 bytes from registers 23, 24 and 25 
    return combinedbytes;
}

void LDC1101::readSPI(uint8_t *data, uint8_t address, uint8_t num_bytes)
{
    // CSB down
    _cs_pin.write(0);
    
    // makes sure the address starts with 1... Why?
    _spiport.write(address | 0x80); //read flag 
    for(int i=0; i < num_bytes ; i++)
    {
        data[i] = _spiport.write(0xFF);
    }
    // CSB up
    _cs_pin.write(1);
}

void LDC1101::writeSPI(uint8_t *data, uint8_t address, uint8_t num_bytes)
{
    // CSB down
    _cs_pin.write(0);
    
    _spiport.write(address); 
    for(int i=0; i < num_bytes ; i++)
    {
        _spiport.write(data[i]);
    }
    // CSB up
    _cs_pin.write(1);
}


// EXTRA test: Get&print values of all variables to verify (to calculate the induction)
// The data will be printed on the screen using RealTerm: baud 9600.
// Begin ***********************************************************
    float LDC1101::get_raw_l()          {_raw_l = readRawCounts(); 
                                        return _raw_l;};        
    float LDC1101::get_fsensor()        {
    uint16_t resp[] = {0, 0, 192, 384, 768, 1536, 3072, 6144};
    _raw_l = readRawCounts();
    _fsensor = (_frequency/(_raw_l*3.0))*resp[(uint8_t)(_responsetime)];                
        return _fsensor;};        
    
    float LDC1101::get_frequency()      {return _frequency;};    
    float LDC1101::get_responsetime()   {return _responsetime;};    
    float LDC1101::get_cap()            {return cap;};
// END ***********************************************************