`uBit.io.logo` might need to be configured as capacitive mode on startup

[microbit-carlos]

It's possible that with the move to uBit.io.logo the default NRF52Pin touch mode is resistive and it might need to be set up to capacitive on startup.

With the latest commit in main, running this code and touching the logo is only registered if I am touching the GND pin as well:

from microbit import *
while True:
    print(pin_logo.is_touched())
    sleep(200)

[microbit-carlos]

There might be some technical reason why Capacitive might or might not be the default for uBit.io.logo, which we'll need to discuss in:

• Default uBit.io.logo touch type should be capacitive. lancaster-university/codal-microbit-v2#411

In the meantime I think we can probably change the mode in the MicroPython side, and if the default changes in the future we can revert it later.

[dpgeorge]

Actually, the problem here is a bit subtle. uBit.io.logo is already of type NRF52Pin and MicroPython is calling NRF52Pin::wasTouched() to get touch information for the pin_logo.was_touched() method. That function's signature is:

int wasTouched( TouchMode touchMode = TouchMode::Capacitative );

So we are already using capacitive touch for pin_logo.was_touched(). Just not pin_logo.is_touched().

If you first run pin_logo.was_touched() it will configure it to capacitive, and then pin_logo.is_touched() actually works in touch mode!

[dpgeorge]

My above statement seems to be true for all pins, not just pin_logo. Eg, run the above while-True loop using pin0 and then run pin0.was_touched() and then run the loop again. The second time the pin seems much more responsive.

[dpgeorge]

In 3074c81 I made pin_logo capacitive at start up.

The remaining thing to do is fix CODAL so that calling wasTouched() without any arguments doesn't change the pin mode.

[microbit-carlos]

Thanks Damien, once we resolve lancaster-university/codal-microbit-v2#411 in CODAL we can also revert that change.
wasTouched() is tracked in:

• NRF52Pin::wasTouched() default mode is capacitative instead of the pin state lancaster-university/codal-microbit-v2#416

[microbit-carlos]

Workaround removed in #213.