============================== OPT4060 driver

1. Overview =============================

This driver supports the Texas Instrument RGBW high resolution color sensor over I2C. https://www.ti.com/lit/gpn/opt4060

The driver supports:

• Raw values for red, green, blue and clear.
• Illuminance values.
• Scaled color values for red, green and blue.
• IIO events for thresholds.
• IIO triggered buffer using both its own data ready trigger and triggers from other drivers.

2. Illuminance calculation =============================

Illuminance is calculated using the wide spectrum green channel.

lux = GREEN_RAW x 2.15e-3

The value is accessed from: /sys/bus/iio/devices/iio:deviceX/in_illuminance_input

See section 8.4.5.2 in the data sheet for additional details.

3. Color scale values =============================

The sensor has different sensitivity for the different color components and compensating factors are exposed from the driver.

The values are accessed from: /sys/bus/iio/devices/iio:deviceX/in_intensity_red_scale /sys/bus/iio/devices/iio:deviceX/in_intensity_green_scale /sys/bus/iio/devices/iio:deviceX/in_intensity_blue_scale

A userspace application can multiply the raw values with the scale values so that for a particular test light source, typically white, the measurement intensity is the same across the different color channels. This is calculated in the following way:

R = RED_RAW x SCALE_RED(2.4) G = GREEN_RAW x SCALE_GREEN(1.0) B = BLUE_RAW x SCALE_BLUE(1.3)

The data sheet suggests using the scaled values to normalize the scaled R, G and B values. This is useful to get a value for the ratio between colors independent of light intensity. A userspace application can do this in the following way:

R_NORMALIZED = R / (R + G + B) G_NORMALIZED = G / (R + G + B) B_NORMALIZED = B / (R + G + B)

See section 8.4.5.2 in the data sheet for additional details.