File content as of revision 0:9d5134074d84:

#include "HTS221.h"


// ------------------------------------------------------------------------------
//jmf  -- define I2C pins and functions to read & write to I2C device

#include <string>
#include "mbed.h"

I2C i2c(PTC11, PTC10);    //SDA, SCL -- define the I2C pins being used

// Read a single unsigned char from addressToRead and return it as a unsigned char
unsigned char HTS221::readRegister(unsigned char slaveAddress, unsigned char ToRead)
{
    char data = ToRead;

    i2c.write(slaveAddress, &data, 1, 0);
    i2c.read(slaveAddress, &data, 1, 0);
    return data;
}

// Writes a single unsigned char (dataToWrite) into regToWrite
int HTS221::writeRegister(unsigned char slaveAddress, unsigned char regToWrite, unsigned char dataToWrite)
{
    const char data[] = {regToWrite, dataToWrite};

    return i2c.write(slaveAddress,data,2,0);
}


//jmf end
// ------------------------------------------------------------------------------

static inline int humidityReady(uint8_t data) {
    return (data & 0x02);
}
static inline int temperatureReady(uint8_t data) {
    return (data & 0x01);
}


HTS221::HTS221(void) : _address(HTS221_ADDRESS)
{
    _temperature = 0;
    _humidity = 0;
}


int HTS221::begin(void)
{
    uint8_t data;

    data = readRegister(_address, WHO_AM_I);
    if (data == WHO_AM_I_RETURN){
        if (activate()){
            storeCalibration();
            return data;
        }
    }

    return 0;
}

int
HTS221::storeCalibration(void)
{
    uint8_t data;
    uint16_t tmp;

    for (int reg=CALIB_START; reg<=CALIB_END; reg++) {
        if ((reg!=CALIB_START+8) && (reg!=CALIB_START+9) && (reg!=CALIB_START+4)) {

            data = readRegister(HTS221_ADDRESS, reg);

            switch (reg) {
            case CALIB_START:
                _h0_rH = data;
                break;
            case CALIB_START+1:
            _h1_rH = data;
            break;
            case CALIB_START+2:
            _T0_degC = data;
            break;
            case CALIB_START+3:
            _T1_degC = data;
            break;

            case CALIB_START+5:
            tmp = _T0_degC;
            _T0_degC = (data&0x3)<<8;
            _T0_degC |= tmp;

            tmp = _T1_degC;
            _T1_degC = ((data&0xC)>>2)<<8;
            _T1_degC |= tmp;
            break;
            case CALIB_START+6:
            _H0_T0 = data;
            break;
            case CALIB_START+7:
            _H0_T0 |= data<<8;
            break;
            case CALIB_START+0xA:
            _H1_T0 = data;
            break;
            case CALIB_START+0xB:
            _H1_T0 |= data <<8;
            break;
            case CALIB_START+0xC:
            _T0_OUT = data;
            break;
            case CALIB_START+0xD:
            _T0_OUT |= data << 8;
            break;
            case CALIB_START+0xE:
            _T1_OUT = data;
            break;
            case CALIB_START+0xF:
            _T1_OUT |= data << 8;
            break;


            case CALIB_START+8:
            case CALIB_START+9:
            case CALIB_START+4:
            //DO NOTHING
            break;

            // to cover any possible error
            default:
                return false;
            } /* switch */
        } /* if */
    }  /* for */
    return true;
}


int
HTS221::activate(void)
{
    uint8_t data;

    data = readRegister(_address, CTRL_REG1);
    data |= POWER_UP;
    data |= ODR0_SET;
    writeRegister(_address, CTRL_REG1, data);

    return true;
}


int HTS221::deactivate(void)
{
    uint8_t data;

    data = readRegister(_address, CTRL_REG1);
    data &= ~POWER_UP;
    writeRegister(_address, CTRL_REG1, data);
    return true;
}


int
HTS221::bduActivate(void)
{
    uint8_t data;

    data = readRegister(_address, CTRL_REG1);
    data |= BDU_SET;
    writeRegister(_address, CTRL_REG1, data);

    return true;
}


int
HTS221::bduDeactivate(void)
{
    uint8_t data;

    data = readRegister(_address, CTRL_REG1);
    data &= ~BDU_SET;
    writeRegister(_address, CTRL_REG1, data);
    return true;
}


int
HTS221::readHumidity(void)
{
    uint8_t data   = 0;
    uint16_t h_out = 0;
    double h_temp  = 0.0;
    double hum     = 0.0;

    data = readRegister(_address, STATUS_REG);

    if (data & HUMIDITY_READY) {
        data = readRegister(_address, HUMIDITY_H_REG);
        h_out = data << 8;  // MSB
        data = readRegister(_address, HUMIDITY_L_REG);
        h_out |= data;      // LSB

        // Decode Humidity
        hum = ((int16_t)(_h1_rH) - (int16_t)(_h0_rH))/2.0;  // remove x2 multiple

        // Calculate humidity in decimal of grade centigrades i.e. 15.0 = 150.
        h_temp = (((int16_t)h_out - (int16_t)_H0_T0) * hum) / ((int16_t)_H1_T0 - (int16_t)_H0_T0);
        hum    = ((int16_t)_h0_rH) / 2.0; // remove x2 multiple
        _humidity = (int16_t)((hum + h_temp)); // provide signed % measurement unit
    }
    return _humidity;
}



double
HTS221::readTemperature(void)
{
    uint8_t data   = 0;
    uint16_t t_out = 0;
    double t_temp  = 0.0;
    double deg     = 0.0;

    data = readRegister(_address, STATUS_REG);

    if (data & TEMPERATURE_READY) {

        data= readRegister(_address, TEMP_H_REG);
        t_out = data  << 8; // MSB
        data = readRegister(_address, TEMP_L_REG);
        t_out |= data;      // LSB

        // Decode Temperature
        deg    = ((int16_t)(_T1_degC) - (int16_t)(_T0_degC))/8.0; // remove x8 multiple

        // Calculate Temperature in decimal of grade centigrades i.e. 15.0 = 150.
        t_temp = (((int16_t)t_out - (int16_t)_T0_OUT) * deg) / ((int16_t)_T1_OUT - (int16_t)_T0_OUT);
        deg    = ((int16_t)_T0_degC) / 8.0;     // remove x8 multiple
        _temperature = deg + t_temp;   // provide signed celsius measurement unit
    }

    return _temperature;
}