---
name: "abtn"
section: "4"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd", "openbsd"]
url: "https://new.carta.tech/abtn"
---

# abtn(4)

ADB Keyboard Special Keys Driver

## NAME

**abtn** – ADB Keyboard Special Keys Driver

## SYNOPSIS

To compile this driver into the kernel, place the following lines in your kernel configuration file:

**device adb**

## DESCRIPTION

The **abtn** driver provides support for the extended Fn keys on Apple notebooks with an ADB interface.

## HARDWARE

The **abtn** driver supports extended keyboard keys (special F-keys) on the following devices:

- Apple iBook Keyboard

- Apple PowerBook Keyboard

## EVENTS

The **abtn** driver sends events to [devd(8)](/devd/8.md) for the following events under the **PMU** system, and **keys** subsystem:

- **brightness** - Generates **up** and **down** notify types matching the pressed key.

- **mute**

- **volume** - Generates **up** and **down** notify types matching the pressed key.

- **eject**

Examples are included in /etc/devd/apple.conf.

## SEE ALSO

[adb(4)](/adb/4.md), [akbd(4)](/akbd/4.md), [cuda(4)](/cuda/4.md), [pmu(4)](/pmu/4.md), [devd(8)](/devd/8.md)

## HISTORY

The **abtn** device driver first appeared in NetBSD 5.0 and was ported to FreeBSD 10.0.

## AUTHORS

The **abtn** driver was written by Tsubai Masanari for NetBSD and ported to FreeBSD by Justin Hibbits.