Source: https://mokxi.com/parts/tcs3200 Updated: 2026-11-09 Part # Color sensor, TCS3200 / TCS230 (GY-31) S2 and S3 pick red, green, blue or clear, and OUT is a square wave whose frequency is that color: read it with pulseIn. See every part - 8 pins - 1 setting - In 1 project Drawn live by the editor's own code, at the size you see it. At a glance ## The Color sensor, TCS3200 / TCS230 (GY-31) in brief What it is, and every setting the properties panel gives it. The TCS3200 color sensor, on the GY-31 board, has no bus and no library. Behind its lens is an 8 by 8 grid of photodiodes, a quarter behind red filters, a quarter green, a quarter blue and a quarter bare, with four white LEDs to light the card. Two pins, S2 and S3, choose which group is read, and the output pin OUT is a square wave whose frequency is how much of that color the sensor sees. S0 and S1 scale the output to 2, 20 or 100 percent, or power the chip down. A sketch times the wave with pulseIn(), one filter at a time. The Mokxi model keeps the scaling ratios, the filters that overlap a little with their neighbors, and the numbers the common sketches print: at 20 percent a white card gives pulses of about 30 microseconds on each color filter and a black card about ten times longer. Noise, infrared and the distance to the card are not modeled. Family Sensors Pins 8 color #d8262e Pins ## 8 pins Named as the editor names them, so a wire lands where you expect it. Pin Role What it does VCC Input or output 2.7 V to 5.5 V. GND Input or output Ground. S0 Input or output Output frequency scaling. S1 Input or output Output frequency scaling. S2 Input or output Which photodiodes drive the output. S3 Input or output Which photodiodes drive the output. OE Input or output Output enable, active low. Low or unconnected, OUT runs; high, it lets go. OUT Output The square wave, 50% duty. How to use it ## How to read a TCS3200 (GY-31) color sensor with an Arduino The project has no microcontroller. VCC goes to 5 V and GND to ground, S0 is tied to 5 V and S1 to ground, which is the 20 percent scaling most sketches use, and OE is tied to ground, which turns the output on. Two slide switches drive S2 and S3, each starting on ground so the sensor starts on the red filter, and a frequency counter on OUT reads the wave. The card in front of the sensor is red. On the red filter the counter reads about 14 kHz. Slide the right switch to select the blue filter and it falls to about 4 kHz. Change the card to white and the red filter reads about 18 kHz, and set it to black and it falls to about a twentieth of that. More of a color means a higher frequency, which is the opposite of what a pulseIn() reading looks like. In a sketch, pulseIn(OUT, LOW) times half a cycle, so at 14 kHz that is about 36 microseconds and the lower the number the more of that color. The filter table is easy to get backward: S2 and S3 low is red, low and high is blue, high and low is clear, and both high is green. Every card here reads as if it were a centimeter from the sensor under its own LEDs with no room light, so calibrate again on real hardware. Part pin Board pin VCC 5 V (2.7 V to 5.5 V) GND Ground S0, S1 S0 high, S1 low: 20 percent scaling S2, S3 Two switches, or two board pins, to choose the filter OE Ground, or unconnected: output on OUT A frequency counter, or a board pin for pulseIn() The chip runs from 2.7 V to 5.5 V, so a 3.3 V ESP32 or Pico drives it directly. Use the same pulseIn() timing on any board. Hold the button This is the simulator itself, running here. Click anything to open it in the editor. Open this project in the editor Read the full tutorial Reading red, green and blue with pulseIn() Common errors ## Common Color sensor, TCS3200 / TCS230 (GY-31) errors and fixes What goes wrong The fix Red and blue readings are swapped. The filter table is not in order. S2 and S3 low is red, low and high is blue, high and low is clear, and both high is green. OUT shows nothing at all. OE is high, or S0 and S1 are both low, which powers the chip down. Take OE low or leave it open, and set S0 and S1 for a scale. A larger number is read as more of the color. pulseIn() measures the length of a pulse, not the frequency. A shorter pulse means a higher frequency, so more of that color. Readings do not match between the simulator and a real sensor. Real readings depend on the distance, the room and the card. Map your values with the cards here, then calibrate again on the hardware. Questions ## Questions and answers ### How does the TCS3200 output a color? As a frequency. S2 and S3 choose the red, green, blue or clear photodiodes, and OUT is a 50 percent duty square wave whose frequency rises with the amount of that color. ### What do S0 and S1 do? They scale the output frequency: low-high is 2 percent, high-low 20 percent, high-high 100 percent and low-low powers the chip down. Most sketches use 20 percent, which an Uno’s pulseIn() keeps up with easily. ### Is the TCS230 the same chip? Yes. The TCS230 is the TCS3200’s earlier name, and the GY-31 board carries it. ### Does the TCS3200 need a library? No. There is no bus. Set the two filter pins, read OUT with pulseIn() and compare the three numbers. How it is modeled ## What is true about the Color sensor, TCS3200 / TCS230 (GY-31), here In its help article’s own words: what the simulation gets right, and where it stops. ### Modeled - The pin table above, and OE and power-down letting OUT go. - The scaling: 2% is a tenth of 20%, which is a fifth of 100%. - Each filter picks up a little of its neighbors, as the real filters overlap, and the clear photodiodes see everything. - The numbers the common sketches print: at 20% a white card gives pulseIn() lows of about 30 us on each color filter, and a black card about ten times longer. From TCS3200 color sensor, in full. Projects ## See the Color sensor, TCS3200 / TCS230 (GY-31) in a project One built-in project uses it. It opens in the editor, already wired. Keep going ## Keep going - Arduino Ultrasonic Sensor (HC-SR04) Tutorial - Arduino LDR Night Light (Photoresistor) - Color sensor, TCS34725 - Light sensor More parts ## The rest of the bench Every one of these is drawn and simulated the same way. Full-size breadboard A real 0.1 inch grid with the rails and the center channel, 63 columns wide. Jumper wires Drag from any pin or hole to any other. Corners snap, and you can drag them. Power A supply rail at the voltage you choose. Ground The other end of every circuit. LED Lights when current flows. Five colors, and the brightness is what your eye would see. Filament lamp A tungsten bulb in a holder: an inrush when it is switched on cold, tens of milliseconds to warm up, and dim on half its voltage. Resistor Any value you like, with the color bands drawn to match. ESP32-C3-DevKitM-1 A RISC-V board that runs your firmware at 160 MHz on the real memory map. Pushbutton A 12 mm tactile switch. Hold it while the simulation runs. Raspberry Pi Pico The RP2040 board on our own Cortex-M0+ core. Pick a program and press Run. Raspberry Pi Pico W Raspberry Pi Pico W (RP2040). The same board and the same pinout as a Pico, with the CYW43439 on it. The WiFi is simulated (no radio; real internet through the Cloud panel’s switch), and the on-board LED, which hangs off that chip rather than off GP25, is driven through the same path. Everything else is the Pico. Raspberry Pi 4 Model B Raspberry Pi 4 Model B: the 40-pin header, driven by main.py with RPi.GPIO or gpiozero. See every part ## Wire up the Color sensor, TCS3200 / TCS230 (GY-31) Open the editor and push it into the breadboard. It is free, and it runs on your own machine. Start building free Open the editor