I tried to use the Arduino Stepper library with the Longan Nano, and it doesn’t work. The Stepper library uses the Arduino micros() function internally for timing purposes, and to me it looks like this function is broken in the Arduino framework. The values returned by the function are monotonically decreasing, until the value -1 is returned continuously.
This can be reproduced with a test sketch for the micros() function.
Is there a place where bugs can be reported against the Arduino framework for the Longan Nano?