I am using a frdm K64f board and want to try out the new mbed OS on it.
My question is libraries I used in classic mbed like for the accelerometer on the board and to control a couple of DC motors, are these compatible with mbed OS?
Or will they need modified to work correctly.
They might be compatible in some cases (depends on how they are implemented - what they use from mbed, which parts of mbed-drivers or other modules, are they using any interrupts or just blocking).
You can simply fetch the library and give it a try to see if it compiles and works. However, as you have noticed we are moving to events (async), and many of libraries in mbed use blocking API. For instance, we will update AnalogIn to provide async methods, and we might deprecate the blocking methods.