@dda Thanks, I had tried 34 in the other Library and it wouldn’t work. But when I inserted the writeByte lines just as you showed, it worked. But i’m still having issues running my IMU via interrupt vs just times (like a fixed 1KHz). The timed approach always works, but the interrupt approach will crash sometimes or lock up. So something still seems off with the m5stack and the MPU9250. Also the magnetometer doesn’t seem to function properly on the m5stack for me, even after the battery pack with magnets is removed.