Colour sensors provide more reliable solutions to complex automation challenges. They are used in a variety of industries, including the food and beverage, automotive, and manufacturing industries, for example, detecting material, detecting colour marks on parts, verifying steps in the manufacturing process, etc. While expensive colour sensors are used in industrial applications, inexpensive sensors such as the TCS230 colour sensor module can be used for less demanding applications.
The TCS3200 colour sensor module has 4 LEDs with the TCS3200 colour sensor IC. The module is designed so that 4 bright LEDs illuminate the object, and reflections from this object hit the TCS3200 colour sensor module IC to recognise the colour of an object. Us its name clear idea of ​​its application, it is essentially used to recognise the colour of an object. It has a wide variety of industrial, medical, and consumer uses. Note that the TCS3200 colour sensor module product was not developed in accordance with the TCS3200 datasheet. In critical applications, failure or malfunction of this product can lead to life-threatening or fatal injuries. Any use by the customer is at the customer’s sole risk.
How Color Sensors Work
White light consists of three basic colours (red, green and blue) that have different wavelengths; these colors combine to form various shades of color
When white light hits a surface, some wavelengths of light are absorbed and others reflected, depending on the properties of the surface material. The color we see is the result of wavelengths reflected from our eyes.
Back to the sensor: A typical color sensor contains a high-intensity white LED that projects a modulated light onto the object. To identify the color of the reflected light, almost all color sensors consist of a colour-sensitive filter grid, also known as a “Bayer filter”, and a number of photodiodes underneath, as shown in the following illustration.
A single-pixel consists of 4 filters, a red, a blue, a green and a transparent filter (no filter). This pattern is also known as the “Bayer pattern”. Each filter lets the light of a single colour to the photodiode underneath, while the clear filter lets the light through unchanged, as shown below. This extra light that falls through the clear filter is a great benefit in poor lighting conditions.
Functional Block Diagram
When light from the object hits the photodiode array, each filter only lets through one color and blocks other colours. Then the output current (I) of this photodiode array is converted into a frequency. This output is in the square waveform. The incident light input changes the current flow through the photodiode as the frequency of the square waves changes; the output square wave frequency is later used to detect the RGB color content to define the colour of the photodiode array (red, green, blue, clear). We can do the frequency scaling with pins S0 and S1.
Colour Sensor Module Pinout
| S0 | S1 | Output Frequency Scaling (f0) | Min o/p Frequency | Typ o/p Frequency |
| 0 | 0 | Power Down Mode | – | – |
| 0 | 1 | The output frequency is 2% of the current to frequency converter’s output. | 10 kHz | 12 kHz |
| 1 | 0 | The output frequency is 20% of the current to frequency converter’s output. | 100 K | 120 K |
| 1 | 1 | The output frequency is 100% of the current to frequency converter’s output. | 500 K | 600 K |
Power down mode
This mode is active when pin S0 and pin S1 are in the LOW state. The output pin is in the high-resistance state after this mode have been activated. The function of this mode is like the OE (Active Low) pin. However, the off mode saves more energy. Compare with OE pin activation (Active Low).
Full-Scale Frequency
Full-scale frequency can be defined as the maximum frequency at which output is stable.
Operating Characteristics of Full-Scale Frequency
The Full-Scale Frequency is different for Red Pass Filter, Green Pass Filter and Blue Pass Filter.
The below figure shows the frequency spectrum diagram. The wavelengths at which Red, Green and Blue colours is relatively responsive are Highlighted.
Now we will see the sensor output of Red Filter, Blue Filter and Green Filter for the wavelengths highlighted in the above figure.
