Perhaps you've heard of the the SPI and I²C digital buses. These are, respectively, 3 wire and 2 wire interconnects that are used to talk to peripheral ICs, such as EEPROMs. But, did you know there is a digital bus that uses only one wire? This project show how to build a digital serial number the can communicate with a host using the 1-Wire Bus Procol. See: https://sites.google.com/site/wayneholder/digital-serial-n
Nice, there's a couple of other 1Wire slave projects you may be interested in: M-o-a-T for AVR: https://github.com/M-o-a-T/owslave and InfernoEmbedded Onewire-softdevice for STM32 (my own): https://github.com/InfernoEmbedded/onewire-softdevice