Sparkfun 9DOF_Razor_IMU Yaw angle not correct

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Anyone using Spark fun 9DOF_Razor_IMUI?

I have used the IMU on jetson tx2 and installed the MIT-Racecar software from https://github.com/mit-racecar/racecar. The software enable the device and publish /imu/data and /imu/mag message. However, I found the yaw angle I computed form IMU orientation was not correct. When I rotate the car orientation by 90 degree, the yaw changed 360 degree. I also used Rviz to visualize the IMU/data message, it also showed the same problem.

I would like to know if anyone is using the device and what software...