MPU9250 | MPU9250 driver for STM32 with HAL using SPI

You need to use a CMAKE_TOOLCHAIN_FILE instead of your hackish compiler change without any sysroot etc...

Research object-oriented programming. Apply encapsulation. Group data depending on object, not similarities - just like you think about them.

Use standard library objects - std::array. Save memory, allow optimization - apply const whenever possible, use constexpr when possible. Research code guidelines and style guides - like https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#S-philosophy and https://google.github.io/styleguide/cppguide.html .

Let's say in pseudocode, you could encapsulate all variables within one object and use member function to calculate the relevant stuff:

you could setup a simple web server on the pi and access that server from any device that's on the same network without going through any fancy setups.

If your pi zero is has wifi or if you can get the adapter, you can easily fire up your server with flask or Django.

You said you used three wires to connect the GY-91 - VIN, SCL and SDA. You didn't mention GND.

You must connect both GND and VIN for it to work. Use another jumper to connect GND to GND on the ESP32 and try again.

[edit: Errno 19 ENODEV means that the module couldn't find the I2C sensor]

The solutions was:

1. Using extern C: I was using extern C, but included them in the regular way as well and that caused the problem.

_{I originally wrote this answer for this Drones.SE thread and am reposting here.}

The configurable scale ranges for the accelerometer, gyroscope, and magnetometer on the MPU-9250 IMU affect the maximum resolution and range of the reported values.

As you increase the full-scale range setting, the maximum value/rate that can be reported by the IMU before the IMU is saturated increases, but the resolution of the value/rate decreases.

Section 3.1 of the datasheet for the Invensense MPU-9250 has a table that states the "Gyroscope ADC Word Length", which represents how large the values reported over the I²C or SPI interfaces are. In this case, the gyro word length is 16 bits. A 16 bit two's complement binary number (explained wonderfully in this video by Ben Eater) can range from -32768 to +32767.

Take the example of the ±500 °/s full-scale range. The unit resolution of the two's complement value reported by the gyro (aka Least Significant Bit/LSB resolution) in the ±500 °/s full-scale range is: 32767 / 500 = 65.534 LSB/(°/s) (degrees per second per LSB). This is not coincidentally labeled in the graph as the "Sensitivity Scale Factor" for the FS_SEL=1 condition.