The TCS3200 color sensor can detect a wide variety of colors based on their wavelength. This sensor is specially useful for color recognition projects such as color matching, color sorting, test strip reading and much more.
The TCS3200 color sensor – shown in the figure below –  uses a TAOS TCS3200 RGB sensor chip to detect color. It also contains four white LEDs that light up the object in front of it.
Specifications:
Power: 2.7V to 5.5V
Size: 28.4 x 28.4mm (1.12 x 1.12″)
Interface: digital TTL
High-resolution conversion of light intensity to frequency
Programmable color and full-scale output frequency
Communicates directly to microcontroller.
 
The TCS3200 has an array of photodiodes with 4 different filters. A photodiode is simply a semiconductor device that converts light into current. The sensor has:
16 photodiodes with red filter – sensitive to red wavelength
16 photodiodes with green filter – sensitive to green wavelength
16 photodiodes with blue filter – sensitive to blue wavelength
16 photodiodes without filter
By selectively choosing the photodiode filter’s readings, you’re able to detect the intensity of the different colors. The sensor has a current-to-frequency converter that converts the photodiodes’ readings into a square wave with a frequency that is proportional to the light intensity of the chosen color. This frequency is then, read by the Arduino.
 
Pin Name
I/O
Description
GND (4)
 
Power supply ground
OE (3)
I
Enable for output frequency (active low)
OUT (6)
O
Output frequency 
S0, S1（1，2）
I
Output frequency scaling selection inputs
S2, S3（7，8）
I
Photodiode type selection inputs
VDD（5）
 
Voltage supply
 
Filter selection
To select the color read by the photodiode, you use the control pins S2 and S3. As the photodiodes are connected in parallel, setting the S2 and S3 LOW and HIGH in different combinations allows you to select different photodidodes. Take a look at the table below:
 
Photodiode type
S2
S3
Red
LOW
LOW
Blue
LOW
HIGH
No filter (clear)
HIGH
LOW
Green
HIGH
HIGH