`pin.get_analog_period_microseconds()` returns `-1` if the pin has not been used yet with `write_analog()`

[microbit-carlos]

In comparison V1 returns the configured period (default is 20ms).

V1:

>>> pin0.get_analog_period_microseconds()
20000

V2:

>>> pin0.get_analog_period_microseconds()
-1
>>> pin0.write_analog(512)
>>> pin0.get_analog_period_microseconds()
20000

Looks like this is by design? as CODAL is not providing the data:

micropython-microbit-v2/src/codal_app/microbithal.cpp

Lines 172 to 179 in fd99f40

	int microbit_hal_pin_get_analog_period_us(int pin) {
	int period = pin_obj[pin]->getAnalogPeriodUs();
	if (period != DEVICE_NOT_SUPPORTED) {
	return period;
	} else {
	return -1;
	}
	}

So if we cannot support this V1 compatibility we might need to update the docs.

[microbit-carlos]

The resolution of this issue should result in NRF52Pin::getAnalogPeriodUs() to not return DEVICE_NOT_SUPPORTED, so this should be fixed with a future CODAL update:

• Driving the speaker pin with hardware PWM produces only noise the first time lancaster-university/codal-microbit-v2#313 (comment)