[Gdeaver]

The problem with home surface mount soldering is the imprecise temperature control. This is a mems device and very sensitive to stress on the package. Invensense has a very specific temperature profile for these chips. They are calibrated at the factory. Mounting stress will make these calibration values way off. Too much stress and the chip will not perform with in spec at all. In the dmp initialization the factory calibration values are read off chip, some registers are set and memory locations initialized then the factory calibration values are read back in. The Pansenti code provides a method of using user calibrated values instead of the factory ones. I have two break out boards and with the sparkfun the values are way off. The china board is very close. I believe this is soldering difference.