---
name: "onewire"
section: "4"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["freebsd", "openbsd"]
url: "https://new.carta.tech/onewire"
---

# onewire(4)

1-Wire bus

## NAME

**onewire** – 1-Wire bus

## SYNOPSIS

**onewire\* at gpioow?** **onewire\* at uow?**

**option ONEWIREVERBOSE**

## DESCRIPTION

1-Wire bus was originally developed by Dallas Semiconductor for connecting integrated circuits. It is commonly used for connecting devices such as electronic keys, EEPROMs, temperature sensors, real-time clocks, security chips, etc.

The **onewire** driver provides a uniform programming interface layer between 1-Wire master controllers and various 1-Wire slave devices. Each 1-Wire master controller attaches a **onewire** framework; several slave devices can then be attached to the **onewire** bus.

The driver supports plugging and unplugging slave devices on the fly.

## SUPPORTED MASTERS

- [gpioow(4)](/gpioow/4.md)

  1-Wire bus bit-banging through GPIO pin

- [uow(4)](/uow/4.md)

  Maxim/Dallas DS2490 USB 1-Wire adapter

## SUPPORTED SLAVES

- [owctr(4)](/owctr/4.md)

  1-Wire counter device

- [owid(4)](/owid/4.md)

  1-Wire ID device

- [owsbm(4)](/owsbm/4.md)

  1-Wire smart battery monitor device

- [owtemp(4)](/owtemp/4.md)

  1-Wire temperature device

## SEE ALSO

[intro(4)](/intro/4.md)

## HISTORY

The **onewire** driver first appeared in OpenBSD 4.0.

## AUTHORS

The **onewire** driver was written by Alexander Yurchenko ⟨*grange@openbsd.org*⟩.