---
name: "owc"
section: "4freebsd"
platform: "linux"
package: "freebsd-manpages"
version: "12.2-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/owc/4freebsd"
---

# owc(4freebsd)

Dallas Semiconductor 1-Wire Controller

## NAME

**owc** – Dallas Semiconductor 1-Wire Controller

## SYNOPSIS

**device** **owc**

## DESCRIPTION

The **owc** module implements Dallas Semiconductor 1-Wire signaling. It attaches the [ow(4)](/ow/4.md) driver 1-Wire bus protocol. The **owc** device implements the Link Layer of the 1-Wire bus protocol stack.

Bit banging a pin on a [gpiobus(4)](/gpiobus/4.md) is the only supported controller. Both standard and overdrive transfer timings are implemented. Strong pull-up functionality needed to support parasitic mode is not implemented.

To enable 1-Wire for FDT systems requires modifying the DTS for your board to add something like:

```
/ {
	...
	onewire {
		compatible = "w1-gpio";
		gpios = <&gpio 4 1>;
	};
	...
};
```

The gpios property describes the GPIO pin the 1-Wire bus is connected to. For more details about the *gpios* property, please consult */usr/src/sys/dts/bindings-gpio.txt*.

On a [device.hints(5)](/device.hints/5.md) based system these values are required for the **owc**:

- *hint.owc.%d.at*

  The **gpiobus** you are attaching to.

- *hint.owc.%d.pins*

  This is a bitmask that defines a pin on the **gpiobus** that is to be used for the 1-Wire bus. For instance, to configure pin 10, use the bitmask of 0x400. Please note that this mask should have only one bit set (any other bits - i.e., pins - will be ignored).

## SEE ALSO

[gpiobus(4)](/gpiobus/4.md), [ow(4)](/ow/4.md), [ow\_temp(4)](/ow_temp/4.md), [owll(9)](/owll/9.md), [own(9)](/own/9.md)

## LEGAL

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

## HISTORY

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

## AUTHORS

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

## CAVEATS

The gpio driver implements timing by busy waiting, which can cause a high load on slower systems.

## BUGS

Overdrive mode has not actually been tested.