File content as of revision 0:6bba2efea51e:

#include "mpl3115a2.h"
 
#define MPL3115A_I2C_ADDRESS                        0xc0  //0x60


MPL3115A2::MPL3115A2(I2C& r) : m_i2c(r)
{
}

MPL3115A2::~MPL3115A2()
{
}

void MPL3115A2::init()
{
    uint8_t regVal;

    //MPL3115Reset( );
    write(CTRL_REG1, 4);
    wait(0.05);
    
    do
    {   // Wait for the RST bit to clear 
        regVal = read( CTRL_REG1);
        //printf("ctrl_reg1:%02x\n", regVal);
    } while( regVal );
   
    write( PT_DATA_CFG_REG, 0x07 ); // Enable data flags 
    write( CTRL_REG3, 0x11 );       // Open drain, active low interrupts 
    write( CTRL_REG4, 0x80 );       // Enable DRDY interrupt 
    write( CTRL_REG5, 0x00 );       // DRDY interrupt routed to INT2 - PTD3 
    write( CTRL_REG1, 0xA9 );       // Active altitude mode, OSR = 32    
                                               
    write( OFF_H_REG, 0xB0 );       // Altitude data offset
    
    SetModeActive( );
}

void MPL3115A2::SetModeActive( )
{
    uint8_t val = read(CTRL_REG1);
    val |= 1;   // set SBYB
    write(CTRL_REG1, val);
}

void MPL3115A2::SetModeStandby( )
{
    uint8_t val = read(CTRL_REG1);
    val &= ~1;   // clear SBYB
    write(CTRL_REG1, val);
}

void MPL3115A2::write(uint8_t a, uint8_t d)
{
    char cmd[2];
    
    cmd[0] = a;
    cmd[1] = d;

    if (m_i2c.write(MPL3115A_I2C_ADDRESS, cmd, 2))
        printf("write-fail %02x %02x\n", cmd[0], cmd[1]);
}

uint8_t MPL3115A2::read(uint8_t a)
{
    char cmd[2];
    
    cmd[0] = a;
    if (m_i2c.write(MPL3115A_I2C_ADDRESS, cmd, 1, true))
        printf("write-fail %02x\n", cmd[0]);
    if (m_i2c.read(MPL3115A_I2C_ADDRESS, cmd, 1))
        printf("read-fail\n");
    //printf("MPL3115::try_read: %x\n", cmd[0]);        
    return cmd[0];
}

/*void MPL3115A2::try_read()
{
    char cmd[2];
    
    cmd[0] = MPL3115_ID;
    if (m_i2c.write(MPL3115A_I2C_ADDRESS, cmd, 1, true))
        printf("write-fail try_read\n");
    if (m_i2c.read(MPL3115A_I2C_ADDRESS, cmd, 1))
        printf("read-fail\n");
    printf("MPL3115::try_read: %x\n", cmd[0]);        
}*/

float MPL3115A2::ReadAltitude( void )
{
    uint8_t counter = 0;
    uint8_t val = 0;
    uint8_t msb = 0, csb = 0, lsb = 0;
    float decimal = 0;

    /*if( MPL3115Initialized == false )
    {
        return 0;
    }*/

    SetModeAltimeter( );
    ToggleOneShot( );

    while( ( val & 0x04 ) != 0x04 )
    {    
        val = read( STATUS_REG);
        wait(0.01); //DelayMs( 10 );
        counter++;
    
        if( counter > 20 )
        {    
            //MPL3115Initialized = false;
            init( );
            SetModeAltimeter( );
            ToggleOneShot( );
            counter = 0;
            while( ( val & 0x04 ) != 0x04 )
            {  
                val = read( STATUS_REG);
                wait(0.01); //DelayMs( 10 );
                counter++;
                if( counter > 20 )
                {
                    return( 0 ); //Error out after max of 512ms for a read
                }
            }
        }
    }

    msb = read( OUT_P_MSB_REG); // High byte of integer part of altitude,  
    csb = read( OUT_P_CSB_REG); // Low byte of integer part of altitude 
    lsb = read( OUT_P_LSB_REG); // Decimal part of altitude in bits 7-4
    
    decimal = ( ( float )( lsb >> 4 ) ) / 16.0;
    //Altitude = ( float )( ( msb << 8 ) | csb ) + decimal;
    Altitude = ( float )( ( int16_t )( ( msb << 8 ) | csb ) ) + decimal;

    return( Altitude );
}

void MPL3115A2::SetModeAltimeter( void )
{
    uint8_t val;

    SetModeStandby( );

    val = read( CTRL_REG1);
    val |= 0x80;                //Set ALT bit
    write( CTRL_REG1, val );

    SetModeActive( );
}

void MPL3115A2::ToggleOneShot( void )
{
    uint8_t val;

    SetModeStandby( );

    val = read( CTRL_REG1);
    val &= ~(0x02);         //Clear OST bit
    write( CTRL_REG1, val );

    val = read( CTRL_REG1);
    val |= 0x02;            //Set OST bit
    write( CTRL_REG1, val );

    SetModeActive( );
}

float MPL3115A2::ReadTemperature( void )
{
    uint8_t counter = 0;
    bool negSign = false;
    uint8_t val = 0;
    uint8_t msb = 0, lsb = 0;

    /*if( MPL3115Initialized == false )
    {
        return 0;
    }*/

    ToggleOneShot( );

    while( ( val & 0x02 ) != 0x02 )
    {    
        val = read( STATUS_REG);
        wait(0.01);
        counter++;
    
        if( counter > 20 )
        { 
            //MPL3115Initialized = false;
            init( );
            ToggleOneShot( );
            counter = 0;
            while( ( val & 0x02 ) != 0x02 )
            {
                val = read( STATUS_REG);
                wait(0.01);
                counter++;
            
                if( counter > 20 )
                { 
                    return( 0 ); //Error out after max of 512ms for a read
                }
            }
                
        }
    }

    msb = read( OUT_T_MSB_REG); // Integer part of temperature 
    lsb = read( OUT_T_LSB_REG); // Decimal part of temperature in bits 7-4

    if( msb > 0x7F )
    {
        val = ~( ( msb << 8 ) + lsb ) + 1;  //2?s complement
        msb = val >> 8;
        lsb = val & 0x00F0; 
        negSign = true;
    }

    if( negSign == true )
    {
        Temperature = 0 - ( msb + ( float )( ( lsb >> 4 ) / 16.0 ) );
    }
    else
    {
        Temperature = msb + ( float )( ( lsb >> 4 ) / 16.0 );
    }

    ToggleOneShot( );

    return( Temperature );
}