Yeah, I am baffled.
I haven't had any issues running the Charlieplexing code, until that wire.begin gets put in.
I have had luck without the Charlieplexing library and the DS3231, directly manipulating the output pins with the usual
{
pinMode( pins[0], OUTPUT );
digitalWrite( pins[0], HIGH );
pinMode( pins[1], OUTPUT );
digitalWrite( pins[1], LOW );
}
where pins[x] calls an array.
I don't get any brightness control, and I do get minor random flickers, which is why I want to use the Charliplexing library, it (normally) works like a charm, in my limited experience.