In case someone is interested in using the LSM9DS1 IMU in PD (I2C interface) this is a project with a customized render I have developed a few years back for a course (but just updated for the custom render which comes with the latest image v0.3.8h).

This has been tested on Bela mounted on top of a BeagleBone Black as well as on top of a BeagleBone Black Wireless (never tested on the Mini).

Before running the project, you have to compile and install the RTIMULib2 https://github.com/RTIMULib/RTIMULib2

Download it (I have it under /root/Bela/libraries/), go to the sub-directory "RTIMULib" and enter te following commands:
mkdir build
cd build
cmake ..
make -j4
sudo make install
sudo ldconfig

It can be useful to compile and run also the command line calibration utility (under Linux/RTIMULibCal, use "make -j4"), to make sure that the board and the IMU communicate properly (if not, ensure you see the "6b" address when running "i2cdetect -y -r 1", change the last digit to the if not using I2C port 1 (as in the attached circuit diagram).

In the customized render.cpp you find additional code in 5 different parts, all beginning with a comment "// MCT4054".

More instructions on how to use are included in _main.pd comments.

The RTIMULib.ini must be in the same project directory (you can change the I2C port - I have tested both 1 and 2 and works well - as well as change IMU-specific options within reasonable ranges - refer to the component datasheet).

Note that in the project options "Make Parameters" is set to "LDLIBS=-lRTIMULib" (otherwise the build won't succeed).

Modules featuring the LSM9DS1 appears to be discontinued, however RTIMULib2 also supports:
InvenSense MPU-9150
STM L3GD20H + LSM303D
STM L3GD20 + LSM303DLHC
STM LSM9DS0
InvenSense MPU-9250
STM L3GD20H + LSM303DLHC
Bosch BMX055
Bosch BNX055

The same project with minimum modification (such as line 20 in RTIMULib.ini) should work also with the above-listed IMU (I haven't tested them!). In render.cpp and _main.c you find several variables, functions, messages with name including "LSM9DS1", which you may want to rename to your IMU part number (not a must, the code should still work...).

I hope this can be useful for someone looking to use IMUs with PD or C++ (it took a while to understand how to do this years ago). These steps have worked in adding the library/custom render in the various Bela image from v0.3.6b to v0.3.8h (when a new render.cpp is released, just copy the code blocks with block comments "// MCT4054" in the equivalent location - line number usually changes).