Color Sensors

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Introduction

A sensor unique to the Meta Environment board is a color sensor. Like ambient light sensors, a color sensor is responsive to light, however they are manufactured to only respond to visible light, typically red, green, and blue, though some models also capture all visible light.

How They Work

Similar to an ambient light sensor, color sensors are also comprised of photodiodes, amplifiers, and ADCs which transform the photocurrents into digital values. To obtain more accurate color readings, additional optical filters can be added to the device to remove infrared and ultra-violet light, and multiple red, green, and blue filtered photodiodes are placed on the sensor.

TCS34725 Block Diagram

TCS34725 Block Diagram

MetaWear Color Sensor

The Meta Environment board comes equipped with an AMS TCS34725 color sensor. The sensor contains a 3×4 array of photodiodes that produce 16-bit digital values corresponding to the intensity of red, green, blue, and clear light.

Specification AMS TCS34725
Temperature Range -40℃ – 85℃
Supply Voltage (VDD) 2.7V – 3.6V
ADC Range 0 – 65535
Gain Settings 4X, 16X, 60X
Current Consumption 235µA

It is important to note that the sensor returns simply returns a digital value representing the light intensity and this value is influenced by the integration time and signal gain.

Applications

Color sensors share several applications with ambient light sensors being that they both sense light. However, with the ability to measure specific colors, color sensors have some unique uses where color is a determining factor. They are most commonly found in automated systems where a product’s color determines what the system should do with it for example: sorting legos by color or verifying RGB colors on LCD panels. Additionally, you can use them to measuring ambient color such as the visible light emitted in a reaction.