MPU9250 version of LowLatencyLogger_MPU6050, originally belongs to Bill Greiman's SDFAT Arduino library. also includes codes from Jeff Rowberg's I2C-MPU library
It logs MPU9250's Accelerometer, Gyroscope and Magnetometer raw data to SD card (my case, Pin 4)
I wanted to run the code without serial communications, therefore I modded the code slightly and serial commands are replaced with digital pin inputs. you might easyily rollback.
As my understanding, MPU9250 reads Magnetometer from independently attached distinct sensor unlike Acc./Gyroscope. therefore it requires waking the magnetometer up before each reading, which requires inevitable delay. This means you never be able to sample 9doF data above ~40Hz (it's a pain in my ass. somebody help me). If magnetometer data occluded, This logger should work around 250hz