The function is modeled after traceback.print_exception(), but unbloated,
and put into existing module to save overhead on adding another module.
Compliant traceback.print_exception() is intended to be implemented in
micropython-lib in terms of sys.print_exception().
This change required refactoring mp_obj_print_exception() to take pfenv_t
interface arguments.
Addresses #751.
Teensy doesn't need to worry about overflows since all of
its timers are only 16-bit.
For PWM, the pulse width needs to be able to vary from 0..period+1
(pulse-width == period+1 corresponds to 100% PWM)
I couldn't test the 0xffffffff cases since we can't currently get a
period that big in python. With a prescaler of 0, that corresponds
to a freq of 0.039 (i.e. cycle every 25.56 seconds), and we can't
set that using freq or period.
I also tested both stmhal and teensy with floats disabled, which
required a few other code changes to compile.
Fix stmhal and teensy print routines to report actual prescaler an period.
Fix teensy build to use soft-float
Add USE_ARDUINO_TOOLCHAIN option to teensy build
