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

# gpioow(4)

1-Wire bus bit-banging through GPIO pin

## NAME

**gpioow** – 1-Wire bus bit-banging through GPIO pin

## SYNOPSIS

**gpioow\* at gpio? offset 0 mask 0x1** **gpioow\* at gpio?** **onewire\* at gpioow?**

## DESCRIPTION

The **gpioow** driver allows bit-banging a 1-Wire bus as a master using one GPIO pin. The pin is used as a data signal. The GPIO pin must be able to drive an output and read an input.

The pin number can be specified in the kernel configuration with the *offset* locator. The *mask* locator should always be 0x1 in this case. The *offset* and *mask* can also be specified when **gpioow** is attached at runtime using the GPIOATTACH [ioctl(2)](/ioctl/2.md) on the [gpio(4)](/gpio/4.md) device.

## SEE ALSO

[gpio(4)](/gpio/4.md), [intro(4)](/intro/4.md), [onewire(4)](/onewire/4.md)

## HISTORY

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

## AUTHORS

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