File content as of revision 2:365c8caabc0e:

#include <stdlib.h>
#include "MS5837.h"


/*
 * Sensor operating function according data sheet
 */

void MS5837::MS5837Init(void)
{
    MS5837Reset();
    MS5837ReadProm();
    return;
}

/* Send soft reset to the sensor */
void MS5837::MS5837Reset(void)
{
    /* transmit out 1 byte reset command */
    ms5837_tx_data[0] = ms5837_reset;
    if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
    printf("send soft reset\n");
    wait_ms(20);
}

/* read the sensor calibration data from rom */
void MS5837::MS5837ReadProm(void)
{
    uint8_t i,j;
    for (i=0; i<8; i++) {
        j = i;
        ms5837_tx_data[0] = ms5837_PROMread + (j<<1);
        if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
        if ( i2c.read( device_address,  ms5837_rx_data, 2 ) );
        C[i]   = ms5837_rx_data[1] + (ms5837_rx_data[0]<<8);
    }
}

/* Start the sensor pressure conversion */
void MS5837::MS5837ConvertD1(void)
{
    ms5837_tx_data[0] = ms5837_convD1;
    if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
}

/* Start the sensor temperature conversion */
void MS5837:: MS5837ConvertD2(void)
{
    ms5837_tx_data[0] = ms5837_convD2;
    if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
}

/* Read the previous started conversion results */
int32_t MS5837::MS5837ReadADC(void)
{
    int32_t adc;
    wait_ms(150);
    ms5837_tx_data[0] = ms5837_ADCread;
    if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
    if ( i2c.read( device_address,  ms5837_rx_data, 3 ) );
    adc = ms5837_rx_data[2] + (ms5837_rx_data[1]<<8) + (ms5837_rx_data[0]<<16);
    //printf("ADC value: %x\n", adc);
    return (adc);
}

/* return the results */
float MS5837::MS5837_Pressure (void)
{
    return P_MS5837;
}
float MS5837::MS5837_Temperature (void)
{
    return T_MS5837;
}

/* Sensor reading and calculation procedure */
void MS5837::Barometer_MS5837(void)
{
    int32_t dT, temp;
    int64_t OFF, SENS, press;
    
    //int32_t dT = 0;
    //int64_t SENS = 0;
    //int64_t OFF = 0;
    int32_t SENSi = 0;
    int32_t OFFi = 0;  
    int32_t Ti = 0;    
    int64_t OFF2 = 0;
    int64_t SENS2 = 0;

    //no need to do this everytime!
    
    
    MS5837ConvertD1();             // start pressure conversion
    D1 = MS5837ReadADC();        // read the pressure value
    MS5837ConvertD2();             // start temperature conversion
    D2 = MS5837ReadADC();         // read the temperature value
    //printf("D1 = %d\n", D1);
    /* calculation according MS5837-01BA data sheet DA5837-01BA_006 */
    dT       = D2 - ((uint32_t)C[5]* 256);
    OFF      = (int64_t)C[2] * (1<<17) + ((int64_t)dT * (int64_t)C[4]) / (1<<6);
    SENS     = (int64_t)C[1] * (1<<16) + ((int64_t)dT * (int64_t)C[3]) / (1<<7);

    temp     = 2000 + ((int64_t)dT * C[6]) / (1<<23);
    press    = (((int64_t)D1 * SENS) / (1<<21) - OFF) / (1<<15);
    if((temp/100)<20){         //Low temp
            //Serial.println("here");
            Ti = (11*int64_t(dT)*int64_t(dT))/(34359738368LL);
            OFFi = (31*(temp-2000)*(temp-2000))/8;
            SENSi = (63*(temp-2000)*(temp-2000))/32;
    }
    
    OFF2 = OFF-OFFi;           //Calculate pressure and temp second order
    SENS2 = SENS-SENSi;
    
    temp = (temp-Ti);
    press = (((D1*SENS2)/2097152l-OFF2)/32768l);
    
    T_MS5837 = (float) temp / 100.0f;                 // result of temperature in deg C in this var
    P_MS5837 = (float) press / 100.0f;                 // result of pressure in mBar in this var
    
}

float MS5837::depth(void) {
    //return (P_MS5837/100)*1.019716;
    return ((P_MS5837*100)-101300)/(fluidDensity*9.80665);
    
}

float MS5837::altitude(void) {
    //return (P_MS5837/100)*1.019716;
    return (1-pow((P_MS5837/1013.25),0.190284))*145366.45*0.3048;
    
}