1-Wire
Single-wire serial bus.

1-Wire is a proprietary single-wire bus developed by Dallas Semiconductor (now Maxim Integrated / Analog Devices). It uses a single signal line in addition to ground; targets can optionally draw power parasitically from the data line during idle periods rather than running a separate power conductor.

Every 1-Wire device ships with a unique factory-burned 64-bit ROM ID: 8 bits of family code, 48 bits of serial number, and 8 bits of CRC. The bus controller selects a device by ROM ID (or addresses all devices with a "Skip ROM" command), then exchanges device-specific data.

The bus defines two timing modes — Standard speed (16.3 Kbps) and Overdrive (around 142 Kbps) — with the latter used by devices that explicitly support faster timing. Typical applications include the DS18B20 temperature sensor, iButton identification keys, EEPROMs, and any low-pin-count peripheral where wiring economy outweighs throughput.