I added functions to query acceleration and gyroscope offset and to write these values back:

getAccOffsets()
getGyrOffsets()
setAccOffsets()
setGyrOffsets()

Still there are issues when re-powering the ICM20948. Found this for ESP32 boards. If you add a delay of 2000 ms at the beginning of setup. it becomes better. Unfortunately still not perfect. No issues at all with Atmega328P based boards.

When re-powered, the initiation sometimes failed. In this case a second attempt will be carried out.

It seems that at least one user had issues to initiate the magnetometer. It only worked after few resets of the sketches.

I have implemented that, in case the magnetometer initiation fails, it is tried again up to ten times in total.

Defining the cs pin variable as int16_t gave an error for some boards. Changed to int.

I noticed that the max SPI clock is 7 MHz according to the data sheet. I adjusted the default to 7 MHz accordingly from 8 MHz which also worked well so far in my tests.

I added the example sketch ICM20948_16_sleep.ino to show how to set the ICM20948 and its magnetometer to sleep mode.

Several changes:

• Replaced #define by constexpr
• Replaced private by protected
• Replaced C-cast by static_cast
• Tidied the constructors

If you want to use both an MPU9250 and an ICM20948 in one sketch it won't compile because of the double definition of xyzFloat. I have separated xyzFloat. You can delete xyzFloat.h and xyzFloat.cpp in one of the libraries if you use both.

I have changed the pitch calculation to a more widely used formula, like here, e.g.:

https://wiki.dfrobot.com/How_to_Use_a_Three-Axis_Accelerometer_for_Tilt_Sensing