MM user manual.
After I2C communication is established and functional, the MM module should be recognized by its ID. The next step is to enable sensors, mag, accel and gyro. Set MagRate to 30Hz, Accel to 100Hz and Gyro 100Hz for example.
I2C_write(MagRate, 30); //30Hz
I2C_write(AccRate, 10); //100Hz
I2C_write(GyroRate, 10); //100Hz
To make MM Blue run, set HostControl register to be 1, like following.
I2C_Write(HostControl, 1); //Run Sentral
Read result from about registers.