Investigate pin_speaker support

[microbit-matt-hillsdon]

I tried to play audio via pin_speaker but I could not get a value to be accepted for the period. Whatever I set was an "invalid period".

More investigation to follow but not a priority for the release as the music APIs are working well.

[microbit-matt-hillsdon]

Giles reports this happens with servo example code too:

I just tried the servo code from https://support.microbit.org/support/solutions/articles/19000101864-using-a-servo-with-the-micro-bit#programming - the V3 editor shows an error ‘line 6 ValueError: invalid period’ in the simulator, but it flashes to a V2 micro:bit and runs without showing an error on display or in serial console

It would be much better for set_analog_period to do nothing in this case so the rest of the program (if any) could be tested.

[microbit-matt-hillsdon]

You can now call set_analog_period (for the sake of servo code etc) though it has no effect on sound. One to discuss to decide if we do anything further.

[microbit-matt-hillsdon]

There's little documentation for pin_speaker and no example code, so for now closing this as an expected limitation of the simulator. We'll consider implementing PWM audio via the pin if there's user demand for it.