add codes for data reading and PCA

Dependencies:   mpu9250_i2c Eigen

Changes

RevisionDateWhoCommit message
2:145ba8262ed2 2019-11-20 shiyaozhanag import libraries default tip
1:28c107f8cf24 2019-11-20 shiyaozhanag add data reading and PCA as comments
0:dbcc46819a5e 2019-11-15 nikoletakuneva Step counter characteristic