There are lots of great devices that need 1-wire interface. They can be temperature sensors (popular DS18S20), RTC and many more. Raspberry Pi doesn’t come with 1-wire interface, so in order to use it you need to emulate through I/O pins or use some sort of expander. Tommi suggests using old Hobby Boards 6-channel 1-wire master hub that can be connected to RasPi using serial interface.
a little hack is needed in order to connect hub to Raspberry Pi. The problem is that hub already has a MAX232 chip level converter. So it has to be removed so DD2480B had direct link to Raspberry Pi board. Another part is Raspberry Pi software that controls hub over serial port. Tommi found a tutorial from internet and followed it to implement his program.
Embedds highly recommends EasyEDA for circuit and PCB design