Negative values not working?

[BorisBrock]

When reading the values via readAccel(int* x, int* y, int* z), three integers are returned. But their values are never negative. Instead small negative values become huge positive numbers (e.g. 65540).

Is that supposed to happen? Am I using it wrong?

PS: I used your example code, unmodified. I compiled with PlatformIO and ran it on a SparkFun ESP32Thing.