Hi, What should be done with the unused pins of a microcontroller? Can they be left just soldered (unconnected) or something additional has to be done? For example, in case of this microcontroller what needs to be done with pins with a status: ''I(pull-up)'' or ''O(Hi-Z)'' or ''-''? Datasheet: http://www.epsondevice.com/webapp/docs_ic/DownloadServlet?id=ID002599
Check the datasheet. The language used in this board is german. Please use the english counterpart https://embdev.net/forum/, if you're unable to communicate in german.
Yes, the pins you don't need can left free, just soldered. Also the pins with I/O can be free. The "-" means that they haven't an input or output and no status. In your case its always for the power supply. They should be connected.
You should on most devices either configure them as an output or, if they are configured as input, enable build in pull-up/-down resistors. This reduces unnecessary currents caused by the undefined state of the input gates.