---
name: "max44009"
section: "4"
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/max44009"
---

# max44009(4)

driver for MAX44009 Ambient Light Sensor

## NAME

**max44009** – driver for MAX44009 Ambient Light Sensor

## SYNOPSIS

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

**device max44009** **device iicbus**

Alternatively, to load the driver as a module at boot time, place the following line in [loader.conf(5)](/loader.conf/5.md):

```
max44009_load="YES"
```

## DESCRIPTION

The **max44009** driver reports illuminance data from MAX44009 Ambient Light Sensor.

The **max44009** driver reports data via [sysctl(8)](/sysctl/8.md) entry in the device's node in the [sysctl(8)](/sysctl/8.md) tree:

- *illuminance*

  The illuminance, in lux units.

On an [FDT(4)](/FDT/4.md) based system the following properties must be set:

- *compatible*

  Must be set to "maxim,max44009".

- *reg*

  The I2C address of **max44009** which can be either 0x4a or 0x4b.

## SEE ALSO

[fdt(4)](/fdt/4.md), [iicbus(4)](/iicbus/4.md), [sysctl(8)](/sysctl/8.md)

## HISTORY

The **max44009** driver and this manual page was written by Andriy Gapon ⟨*avg@FreeBSD.org*⟩.

## BUGS

The **max44009** driver does not support illuminance thresholds and the corresponding interrupt.