---
name: "asmc"
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/asmc/4"
---

# asmc(4)

Apple System Management Controller (SMC)

## NAME

**asmc** – Apple System Management Controller (SMC)

## SYNOPSIS

**asmc0 at acpi?**

## DESCRIPTION

The **asmc** driver provides support for the Apple System Management Controller (SMC), as found in Intel based Apple devices.

The driver possesses a collection of temperature, fan, light, and acceleration sensor values which are made available through the [sysctl(8)](/sysctl/8.md) interface.

If available, the keyboard backlight is enabled by the driver and can be adjusted using the [wsconsctl(8)](/wsconsctl/8.md) variable *keyboard.backlight*.

## SEE ALSO

[acpi(4)](/acpi/4.md), [intro(4)](/intro/4.md), [sensorsd(8)](/sensorsd/8.md), [sysctl(8)](/sysctl/8.md), [wsconsctl(8)](/wsconsctl/8.md)

## HISTORY

The **asmc** driver first appeared in OpenBSD 5.9.

## AUTHORS

The **asmc** driver was written by Joerg Jung ⟨*jung@openbsd.org*⟩.

## CAVEATS

Light sensor values may not be available on older products.

Acceleration sensors are not available and the associated interrupt handling is not implemented.

Besides the sensors, the huge amount of other functions and information available from the SMC is not supported.