TCS34725 + ESP32: Pinout, Wiring Diagram and Working Code

What are the TCS34725 module pins?

The TCS34725 chip itself has five functional pins: VDD, SCL, GND, INT and SDA (ams-OSRAM datasheet, pin description). The breakout adds a voltage regulator and a white illuminator LED, so the module header carries a few extra pins. Our listing names VIN, GND, SDA and SCL in its wiring notes; the chip datasheet supplies the INT function. The table lists pin names only: the catalogue photo is too small to read the header order, so match each wire to the silkscreen on your board.

TCS34725 module pins (names, not header order)

Pin	Function	Source
VIN	Module supply input; the listing says 3.3 V or 5 V via the on-board regulator	Compoden listing
GND	Ground	Chip datasheet + listing
SDA	I2C data	Chip datasheet + listing
SCL	I2C clock	Chip datasheet + listing
INT	Interrupt output, open-drain, active low (optional)	Chip datasheet
LED	Controls the board's white illuminator LED (board-specific, not in the chip datasheet)	Board design; confirm on yours
3V3	3.3 V rail of the module; do not use as your supply input unless your board's documentation says so	Board design; confirm on yours

How do you wire the TCS34725 to an ESP32?

TCS34725 to ESP32 DevKit (30-pin) wiring

TCS34725 pin	ESP32 DevKit pin	Why this pin
VIN	3V3	Keeps the module and its I2C pull-ups at 3.3 V, which ESP32 pins accept
GND	GND	Common ground
SDA	GPIO21	Default I2C data pin of the ESP32 Arduino core
SCL	GPIO22	Default I2C clock pin of the ESP32 Arduino core
LED	Not connected	Optional illuminator control; test without it first
INT	Not connected	Only needed for interrupt-driven reading

Which ESP32 pins should you avoid?

Every GPIO choice on this page follows the same rules for the 30-pin ESP32-WROOM-32 DevKit (the board Compoden stocks as the ESP32 30-pin CP2102 development board). Espressif's ESP32 GPIO reference is the source:

• Never use GPIO6–11. They connect to the module's SPI flash.
• Avoid the strapping pins GPIO0, 2, 5, 12 and 15 for sensors. Their level at reset decides boot mode and flash voltage, so a sensor holding one of them can stop the board booting. GPIO0 is not even on the 30-pin header; it only goes to the BOOT button.
• GPIO34, 35, 36 and 39 are input-only and have no internal pull-up or pull-down. They are ideal for analog inputs and useless for outputs or clocks.
• Use ADC1 (GPIO32–39) for analog readings. ADC2 pins (GPIO0, 2, 4, 12–15, 25–27) cannot be read while Wi-Fi is running.
• Leave GPIO1 and GPIO3 alone. They carry the USB serial link used for uploads and the Serial Monitor.
• ESP32 GPIOs are 3.3 V only. They are not 5 V tolerant.

What voltage does the TCS34725 need?

The ams-OSRAM datasheet gives the TCS34725 chip a supply range of 2.7–3.6 V (3 V typical) and an absolute maximum of 3.8 V. The TCS34725 variant's I2C inputs are referenced to VDD, which suits a 3.3 V ESP32 directly. The module's regulator is what lets the listing accept 5 V on VIN; the chip itself must never see 5 V. With VIN on the ESP32's 3V3 pin, everything on the bus stays at 3.3 V.

The listing states that pull-up resistors are already fitted, so you do not need external ones on SDA and SCL for a short connection.

Working Arduino code for the TCS34725 on ESP32

No extra library is needed: the sketch uses the registers from the ams-OSRAM datasheet directly. It checks the ID register, sets a 154 ms integration time and 4x gain, powers the sensor on, then prints raw counts whenever the STATUS register reports a finished integration. Raw counts are not calibrated colour values: compare them against readings of known reference colours under the same light.

// TCS34725 colour sensor + ESP32 DevKit (ESP32-WROOM-32)
// Wiring: VIN -> 3V3, GND -> GND, SDA -> GPIO21, SCL -> GPIO22 (LED and INT unconnected)
// Registers from the ams-OSRAM TCS3472 datasheet: address 0x29, COMMAND bit 0x80,
// auto-increment 0xA0, ENABLE 0x00, ATIME 0x01, CONTROL 0x0F, ID 0x12, STATUS 0x13, data 0x14-0x1B.
#include <Wire.h>

const int SDA_PIN = 21;
const int SCL_PIN = 22;
const uint8_t TCS_ADDR = 0x29;

void writeReg(uint8_t reg, uint8_t value) {
  Wire.beginTransmission(TCS_ADDR);
  Wire.write(0x80 | reg);          // COMMAND bit + register address
  Wire.write(value);
  Wire.endTransmission();
}

uint8_t readReg(uint8_t reg) {
  Wire.beginTransmission(TCS_ADDR);
  Wire.write(0x80 | reg);
  Wire.endTransmission(false);
  Wire.requestFrom(TCS_ADDR, (uint8_t)1);
  return Wire.available() ? Wire.read() : 0;
}

void setup() {
  Serial.begin(115200);
  Wire.begin(SDA_PIN, SCL_PIN);
  uint8_t id = readReg(0x12);      // datasheet: 0x44 = TCS34725, 0x4D = TCS34727
  if (id != 0x44 && id != 0x4D) {
    Serial.printf("TCS34725 not found (ID 0x%02X). Check VIN, GND, SDA and SCL.\n", id);
    while (true) delay(1000);
  }
  writeReg(0x01, 0xC0);            // ATIME: (256 - 0xC0) x 2.4 ms = 154 ms integration
  writeReg(0x0F, 0x01);            // CONTROL: AGAIN = 4x
  writeReg(0x00, 0x01);            // ENABLE: PON (power on)
  delay(3);                        // datasheet: at least 2.4 ms after PON
  writeReg(0x00, 0x03);            // ENABLE: PON + AEN (start RGBC)
  Serial.println("TCS34725 ready");
}

void loop() {
  if (!(readReg(0x13) & 0x01)) {   // STATUS.AVALID: integration finished
    delay(10);
    return;
  }
  Wire.beginTransmission(TCS_ADDR);
  Wire.write(0xA0 | 0x14);         // auto-increment read starting at CDATAL
  Wire.endTransmission(false);
  Wire.requestFrom(TCS_ADDR, (uint8_t)8);
  uint16_t v[4] = {0};             // clear, red, green, blue
  for (int i = 0; i < 4 && Wire.available() >= 2; i++) {
    uint8_t lo = Wire.read();
    uint8_t hi = Wire.read();
    v[i] = (uint16_t)hi << 8 | lo;
  }
  Serial.printf("R=%u G=%u B=%u Clear=%u\n", v[1], v[2], v[3], v[0]);
  delay(500);
}

Compile check: this exact sketch compiled for the esp32:esp32:esp32 board (ESP32 Dev Module, ESP32 Arduino core 3.3.10) on 5 October 2026. A clean compile proves the code and libraries agree. It does not prove your wiring, so test it on the bench with the Serial Monitor at 115200 baud.

Common mistakes with the TCS34725 and ESP32

• Feeding 5 V into the 3V3 pin. Use VIN for supply; the chip's absolute maximum is 3.8 V.
• Two sensors on one bus. The datasheet lists a single I2C address (0x29) for the TCS34725, so two modules on the same SDA/SCL clash. Use the ESP32's second I2C controller (Wire1) on two other free GPIOs.
• Sketch reports an unexpected ID. The datasheet lists 0x44 for TCS34725 and 0x4D for TCS34727 in register 0x12. Any other value means a wiring fault or a different part.
• Saturated readings in sunlight. Lower the gain or the integration time, or shade the sensor.
• Wiring SDA/SCL to GPIO34–39. Those pins are input-only and cannot drive an I2C bus.
• Expecting true colour without calibration. Light source, distance and the board's own LED all change the raw counts.

Where can you get the parts?

Parts used in this guide (Compoden catalogue)

Item	Role	Link
TCS34725 RGB colour sensor module	Colour and light sensing over I2C	View TCS34725 module
ESP32 30-pin CP2102 development board	Controller with Wi-Fi and Bluetooth	View ESP32 board

Want this sensor in a bigger build? Describe the whole device in Soldr, for example “I want to build a colour sorter with an ESP32, a TCS34725 and a servo”. Soldr returns the exact parts, a wiring map and code that compiles, all from one parts list, so the pins in the code match the pins in the wiring. Compoden stocks the parts and delivers across India.

Sources

Chip pins, voltages, I2C address, registers and ID values: ams-OSRAM TCS3472 datasheet DS000390. ESP32 pin rules: Espressif ESP32 GPIO reference. Module supply, pull-ups and pin names: the Compoden listing.

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Frequently asked questions

Which ESP32 pins should I use for the TCS34725?

Use GPIO21 for SDA and GPIO22 for SCL, the ESP32 Arduino core's default I2C pins. Power the module's VIN from 3V3 and connect GND. LED and INT can stay unconnected.

What is the TCS34725 I2C address?

0x29. The datasheet lists one fixed address for the TCS34725, so a second sensor needs the ESP32's second I2C bus.

Can the TCS34725 run on 5 V?

The chip cannot: its supply range is 2.7 to 3.6 V. The module's regulator lets VIN accept 5 V according to the listing, but with an ESP32 there is no reason to; power VIN from 3V3.