This is a summary of the operations that are done to use the MPL3115A2.

8-bit I2C address is 0xc0.

To configure the device, put values in these two registers.
    Write to the CTRL_REG1 control register (0x26) a byte with:
	bit 0 (SBYS) set to 1 (active mode)
	bits 5:3 (OS2,OS1,OS0) set to 111 (oversample = 128)
	bit 7 (ALT) set to 1 (altimeter mode)
    Write to the PT_DATA_CFG register (0x13) a byte with:
	bit 2 (DREM) set to 1
	bit 0 (TDEFE) set to 1

To read results, read the DR_STATUS register (0x06) and check the TDR bit (1).
If the bit is a one there is data that can be retrieved.  If the bit is zero,
wait and read the DR_STATUS register again.

If data is available, read 5 bytes starting with the OUT_P_MSB register (0x01).  This
reads registers 0x01 through 0x05.

Pressure (altitude) data is in the first three of these registers.  Temperature
data is in the last two.  See page 21 of the datasheet for how the values are
stored in these bytes.