TCS34725 colour sensor with ESP32

Specifications

Power and logic levels

3.3 V: check your module first

ESP32 pins, including those on a display board's connectors, work at 3.3 V and are not 5 V tolerant. Modules differ, so if in doubt, measure the signal before you connect it.

Wiring

Arduino code

#include <Wire.h>

const int SDA_PIN = 8, SCL_PIN = 9;
const uint8_t ADDR = 0x29;
const uint8_t CMD = 0x80, AUTO_INC = 0x20;

void writeReg(uint8_t reg, uint8_t value) {
  Wire.beginTransmission(ADDR);
  Wire.write(CMD | reg); Wire.write(value);
  Wire.endTransmission();
}

uint16_t read16(uint8_t reg) {
  Wire.beginTransmission(ADDR);
  Wire.write(CMD | AUTO_INC | reg);
  Wire.endTransmission();
  Wire.requestFrom(ADDR, (uint8_t)2);
  uint16_t v = Wire.read();
  return v | (Wire.read() << 8);
}

void setup() {
  Serial.begin(115200);
  Wire.begin(SDA_PIN, SCL_PIN);
  writeReg(0x00, 0x01);               // power on
  delay(3);
  writeReg(0x00, 0x03);               // ADC on
  writeReg(0x01, 0xC0);               // 64 cycles, about 154 ms
  writeReg(0x0F, 0x01);               // gain 4
}

void loop() {
  delay(200);
  float c = read16(0x14);
  if (c == 0) return;
  Serial.printf("clear %.0f  r %.2f  g %.2f  b %.2f\n", c,
                read16(0x16) / c, read16(0x18) / c, read16(0x1A) / c);
}

No extra library needed. Compiled for ESP32-S3 with arduino-esp32 3.x. Not yet tested by us on a physical sensor. Change the pins to match your board.

On a display

Read the value in your sketch and pass it to a label, or send it over MQTT and show it with an MQTT value in the editor.

Boards with a ready connector

Only boards whose connectors we have surveyed. Others may still work on free GPIOs.

Good to know

• Control the light for repeatable results.
• Compare ratios, not raw values.
• Saturation at 65535 ruins a reading.
• The LED stays on unless you ground it.

What it is good for

• Colour sorting
• Liquid and test strip checks
• Ambient colour tint display

FAQ

Sources

• https://esphome.io/api/tcs34725_8cpp_source.html
• https://protosupplies.com/product/tcs34725-rgb-color-sensor-module/
• https://git.sudo.is/home-assistant/esphome-docs/src/branch/current/components/sensor/tcs34725.rst

Related parts

• BH1750
• LDR photoresistor