I have the AltIMU-10 v4 wired to my rasperry pi using SCL goes to SCL. SDA goes to SDA, GND goes to GND, and 3v3 power goes to VDD.
The code is fairly large so I am just going to post the parts that have to do with the barometer. Also this is written in python.
b.write_byte_data(LPS, LPS_CTRL_1, 0b11000010)
b.write_byte_data(LPS, LPS_CTRL_2, 0b00000010)
pressureTempLoop = twos_comp_combine(b.read_byte_data(LPS, PRESS_H), b.read_byte_data(LPS, PRESS_L))
pressureLoop = twos_comp_combine(pressureTempLoop, b.read_byte_data(LPS, PRESS_XL))
pressureLoop = convert_barometer(pressureLoop)#converts to usable values
It then goes through a loop for 5 seconds taking readings. The first couple readings are around 994 then out of nowhere it drops down to 0 and then goes to something like -.20123102040 where it says around until the program is done.