one_shot.c

  // set one shot reading
  register_data = MPL3115A2_CTRL_REG1_OST |
                  MPL3115A2_CTRL_REG1_BAR;  
  Wire.beginTransmission(MPL3115A2_ADDRESS);
  Wire.write(MPL3115A2_CTRL_REG1);
  Wire.write(register_data);
  Wire.endTransmission(true);

  // wait for one shot bit to auto clear
  bool ready = false;
  while(!ready) {
    Wire.beginTransmission(MPL3115A2_ADDRESS);
    Wire.write(MPL3115A2_CTRL_REG1);
    Wire.endTransmission(false);
    Wire.requestFrom(MPL3115A2_ADDRESS, 1, true);
    register_data = Wire.read();
    ready = !(register_data & MPL3115A2_CTRL_REG1_OST);
  }
  
  // read 3 bytes for barometer + 2 bytes for temp
  Wire.beginTransmission(MPL3115A2_ADDRESS);
  Wire.write(0x01);
  Wire.endTransmission(false);
  Wire.requestFrom(MPL3115A2_ADDRESS, 5, true);

  uint32_t _pressure = Wire.read();  // OUT_P_MSB
  _pressure <<= 8;
  _pressure |= Wire.read();          // OUT_P_CSB
  _pressure <<= 8;
  _pressure |= Wire.read();          // OUT_P_LSB
  _pressure >>= 4;
  float pressure = _pressure;
  pressure /= 4.0;
  
  int16_t _temp = Wire.read(); // OUT_T_MSB
  _temp <<= 8;
  _temp |= Wire.read();        // OUT_T_LSB
  _temp >>= 4;
  if (_temp & 0x800) {
    _temp |= 0xF000; 
  }
  float temp = _temp;
  temp /= 16;