Port manipulation issue/question

[SpenceKonde]

Maybe not an issue, but why do you do this?

        /* Enable all UPDI port pull-ups */   
        PORT(UPDI_PORT) = 0xFF;

        /* Enable all LED port pull-ups, except for the LED pin */   
        PORT(LED_PORT) = 0xFF - (1 << LED_PIN);

Also, as an aside, on XTINY (ahem, tinyAVR 0-series and 1-series), as well as megaAVR 0-series) that doesn't even do what the comment says, as the pullup is controlled by the PINnCTRL register instead...

Definitely not intended behavior:
You have an LED_PORT and LED_PIN - but you never set DDR for it so it never turns on - it looks like you meant to do that here?

        /* Enable LED */   
        PORT(LED_PORT) |= (1 << LED_PIN);

Bloody hell, it took me like half a dozen edits to get linebreaks into the code blocks!

[SpenceKonde]

As an aside, for proof that it's not necessary to turn on the pullups, consider the fact that you... don't do it on the XTINY parts.

VPORTx.OUT does not emulate the old pullup behavior of classic AVRs, setting an input high this way does not turn on the pullups..

[ElTangas]

Probably I enabled the pullups to avoid letting the inputs floating, I do this out of habit sometimes but it's not really necessary.

Regarding the pullup activation not working on AVR-0/1, I only found out about this after writing that code and forgot about it.