1-Wire

An iButton in a plastic fob, as used for Istanbul Akbil smart ticket
A Java ring with an embedded iButton

1-Wire is a wired half-duplex serial bus designed by Dallas Semiconductor that provides low-speed (16.3 kbit/s[1]) data communication and supply voltage over a single conductor.[2]

1-Wire is similar in concept to I2C, but with lower data rates and longer range. It is typically used to communicate with small inexpensive devices such as digital thermometers and weather instruments. A network of 1-Wire devices with an associated master device is called a MicroLAN. The protocol is also used in small electronic keys known as a Dallas key or iButton.

One distinctive feature of the bus is the possibility of using only two conductors — data and ground. To accomplish this, 1-Wire devices integrate a small capacitor (~800 pF) to store charge, which powers the device during periods when the data line is active.

  1. ^ "Reading and Writing 1-Wire Devices Through Serial Interfaces". Maxim Integrated. Retrieved 2022-12-21.
  2. ^ "Overview of 1-Wire Technology and Its Use". Analog Devices. Archived from the original on 2023-06-27. Retrieved 2023-07-21.