MPU9150 Accelerometer Readings

Hi Guys,

I've just upgraded from an MPU6000 and an external magnetometer to an MPU9150 and came across an accuracy issue.

My MPU6000 (a whole batch of them) were very accurate as when laid flat, the X and Y axis of the accelerometer were near 0 and the z axis was outputting 4000-4100 LSB @ 8g range which is roughly equivalent to 1g.

However, with my new MPU9150s, I'm getting MUCH smaller values for z axis when laid flat, around 3000 which seems like too big a number for just a calibration issue. Furthermore, when I flip the device directly upside down, the value turns to -5100. This means theres a large offset but the TOTAL of these values still equal ~4096 x 2 = 8092. This happens with the whole batch of MPU9150s I have received which makes me think only 2 problems could cause this, my code or a faulty batch. My code is more or less the same as mpu6000 which worked fine so its not like I dont know how to operate it.

Any help would be much appreciated!

Kind Regards,

Cyrus