---
name: "owll"
section: "9"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/owll"
---

# owll(9)

Dallas Semiconductor 1-Wire Link Layer Interface

## NAME

**owll**, **OWLL\_WRITE\_ONE**, **OWLL\_WRITE\_ZERO**, **OWLL\_READ\_DATA**, **OWLL\_REASET\_AND\_PRESENCE** – Dallas Semiconductor 1-Wire Link Layer Interface

## SYNOPSIS

*int*\

**OWLL\_WRITE\_ONE**(*device\_t lldev*, *struct ow\_timing \*timing*);

*int*\

**OWLL\_WRITE\_ZERO**(*device\_t lldev*, *struct ow\_timing \*timing*);

*int*\

**OWLL\_READ\_DATA**(*device\_t lldev*, *struct ow\_timing \*timing*, *int \*bit*);

*int*\

**OWLL\_RESET\_AND\_PRESENCE**(*device\_t lldev*, *struct ow\_timing \*timing*, *int \*bit*);

## DESCRIPTION

The **owll** interface provides access to the link layer of the Dallas Semiconductor 1-Wire from upper layers of the protocol.

**OWLL\_WRITE\_ONE**() and **OWLL\_WRITE\_ZERO**() writes a one bit or a zero bit respectively on the 1-Wire bus.

**OWLL\_READ\_DATA**() reads one bit from the 1-Wire bus. This is often referred to as a “Read Time Slot” in the 1-Wire device data sheets.

The **OWLL\_RESET\_AND\_PRESENCE**() function starts a reset sequence and detects if any device(s) are present on the bus. This is the beginning of all 1-Wire transactions.

## NOTES

This interface is intended to be used only by the [ow(4)](/ow/4.md) device to talk to the low-level bus. By convention, the device that implements this interface is called [owc(4)](/owc/4.md). Only devices that implement [own(9)](/own/9.md) should call these interfaces.

## SEE ALSO

[ow(4)](/ow/4.md), [owc(4)](/owc/4.md), [own(9)](/own/9.md)

## LEGAL

1-Wire is a registered trademark of Maxim Integrated Products, Inc.

## HISTORY

The **owll** driver first appeared in FreeBSD 11.0.

## AUTHORS

The **owll** device driver and this manual page were written by Warner Losh.