hi,

So I could connect directly to P1-3 pins with no additional resistor? That would be good.

You should look at datasheet of the 1-wire device you work with. There are some 1-wire devices which utilize "parasite power" from signal line. In this case I suggest to keep external pull-up resistor otherwise it may occurs that the weak internal pull-up of MCU will not be able to produce enough current to charge parasite capacitor within time slot (especially if high-speed mode used).

Regards,
Oleg