The protocol operates over a single data line without a clock signal. The 1-Wire protocol is a single-wire interface for low-speed data communication in microcontrollers and computers. Most of these 1-wire slave devices are products of (what’s now) Maxim Integrated. The 1-Wire protocol is used by temperature sensors, real-time clocks, timers, EEPROMs, and the popular iButton. And despite a low power consumption, it can communicate data over relatively long distances. It offers a simple hardware implementation and an extremely low-power footprint.Īlthough the hardware is simple, the software implementation on the microcontroller side is highly complex. The data speeds in the 1-Wire protocol are low compared to other standard serial-data communication protocols (like UART, I2C, and SPI), but the 1-wire bus is extremely economical in production and operation. The bus can be overdriven to a maximum data speed of 125 kbps. This is a low-speed serial communication standard, with a typical data speed of 15.4 kbps. Every master device is identified by a 64-bit address, stored within each one-wire slave device’s ROM. What they can do is indicate their presence over the bus when the master resets. The master device is solely responsible for the read and write operations of the slave devices, so they cannot initiate a data transfer on their own. Instead, the slave devices are internally clocked and synchronized with a signal from the master device. This protocol does not use a clock signal. However, as slave devices are added to the bus, their polling by the master device might take more time. It’s possible to connect up to 100-slave, 1-wire devices, with a 1-wire standard bus.

An additional wire might be necessary, depending on the power mode.Ī 1-wire standard has a master and slave configuration, where there can only be one master device, a computer or microcontroller, and several slave devices. Although this protocol is classified as a 1-wire standard, at least two wires are required in the 1-wire standard bus - one for the data and/or power supply and another for the ground return.

The 1-Wire protocol is a single-wire interface, half-duplex, bidirectional, low-speed and power, long-distance serial-data communication protocol.

What is one wire library