Mic LED does not turn off when in low power state

[microbit-mark]

In this program, the micro:bit enters a sleep state, but the mic LED remains lit.

https://makecode.microbit.org/_KbWfyw3zh3PT

I expect that changing this is blocked by lancaster-university/codal-microbit-v2#97, but this seems like a counterintuitive experience for people using the extension. Are we really saving power if the LED is always lit?

cc @jaustin @martinwork

[martinwork]

Thanks @microbit-mark. I didn't think about that. I think you're right that it comes under the same heading as lancaster-university/codal-microbit-v2#97.

CODAL will be shutting down other components, including the ADC and LEDs, which will save power. Moving the "show icon" block out into "on start" shows that.

I'd feel safer knowing that the light would be on all the time, if micro:bit was going to power up every so often and record me.

I wonder whether the sound values recorded are different depending on whether micro:bit has been in low power mode.

My understanding is that the microphone light is turned on by MakeCode, rather than CODAL.
https://github.com/microsoft/pxt-common-packages/blob/master/libs/microphone/microphonehw.cpp#L41

The macros are defined here:
https://github.com/lancaster-university/codal-microbit-v2/blob/master/model/MicroBit.h#L323

CODAL might turn it off here, maybe (except I think DEEP_SLEEP_GPIO_OUTPUTS is not enabled):
https://github.com/lancaster-university/codal-microbit-v2/blob/master/model/MicroBitIO.cpp#L284