The BU27034ANUC Ambient Light Sensor

The original BU27034NUC sensor was redesigned. The new sensor is BU27034ANUC.

The ROHM BU27034ANUC is a digital Ambient Light Sensor IC with I²C bus interface. This IC can be used for obtaining ambient light data for example for adjusting LCD and backlight power of TV and mobile phone. It is capable of detecting a very wide range of illuminance.

Resources

Data sheet

Linux Driver

The old BU27034NUC upstream driver code was re-written to support the new BU27034ANUC variant. The patches converting the old driver to work with the new sensor variant were first merged in the Linux v6.12-rc1 in the Linux tree. Please note that the old upstream device driver is not working with the new sensor. Also, the new driver will not work with the old sensor. The device-tree compatible was also changed to reflect this. Changes are expected to be officially relased at Linux v6.12.

Commits converting support for BU27034NUC to BU27034ANUC

3c9edf76791e (“dt-bindings: iio: BU27034 => BU27034ANUC”)
dd77c0ff9936 (“bu27034: ROHM BU27034NUC to BU27034ANUC”)
acfc80c702fc (“bu27034: ROHM BU27034NUC to BU27034ANUC drop data2”)
bb1059815f56 (“bu27034: ROHM BU27034ANUC correct gains and times”)
eb13959e2dea (“bu27034: ROHM BU27034ANUC correct lux calculation”)

Devicetree example:

    i2c {
      #address-cells = <1>;
      #size-cells = <0>;
      sensor@38 {
        compatible = rohm,bu27034anuc;
        reg = <0x38>;
        vdd-supply = <&vdd>;
      };
    };

Where,

“compatible” must be “rohm,bu27034anuc” for the BU27034ANUC.
“reg” must be device’s I2C address.
vdd-supply = <&vdd> refers to the regulator supplying power to the device.

See the binding document for more information.

Support

Please use the regular upstream maintenance information for support. The maintenance information can be found from the linux MAINTAINERS file. You can read the MAINTAINERS manually or use the get_maintainer.pl

Known issues

We strongly recommend using the latest upstream version of the driver as plenty of fixes are done to the drivers by the Linux kernel community and there is no database for all known issues. Issues spotted by us during development (like adding support for new hardware or improving feature coverage) may have been reported to the issue tracker.

Information below concerns the old BU27034NUC and is obsolete. It is here only to show the differencies for those who might have obtained the old device driver.

ROHM BU27034 Ambient Light Sensor

ROHM BU27034 is an ambient light sesnor with 3 channels and 3 photo diodes capable of detecting a very wide range of illuminance. Typical application is adjusting LCD and backlight power of TVs and mobile phones.

BU27034 supports very large scale of gain settings from 1x up-to 4096x. Additionally the measurement time can be adjusted.

Data sheet is available.

Linux

The ROHM Finland SWDC has created an IIO driver in collaboration with the Linux kernel community. Driver is merged to the upstream Linux v6.4.