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Whatever color the TCS34725 sensor "sees" is reproduced on the orb on top of the cube. The switch in front is hardwired to the LED light on the front of the sensor because we found the LED annoying and most of the times unnecessary.
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Bill of Materials....
Wire per the comments in the Arduino sketch below and you should get this:
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// Read Color Sensor. Mimic color on RGB LED sees
// https://www.whiskeytangohotel.com/
// JUNE 2026
// Arduino Nano but, must selected under Tools → Processor:
// ATmega328P (Old Bootloader) or suffer the avrdude error.
#include <Wire.h>
#include "Adafruit_TCS34725.h"
// TCS34725 SDA pin should be connected to A4
// TCS34725 SCL pin should be connected to A5
// TCS34725 GND to GND
// TCS34725 3.3V to 5V (Vin is No Connect)
// TCS34725 LED goes to hardwired switch
// Define pins for RGB LED
const int RED_PIN = 10;
const int GREEN_PIN = 9;
const int BLUE_PIN = 11;
// Define digital pin for TCS34725 LED control
const int SENSOR_LED_PIN = 6; // Not used, this LED is controlled with a hardwired switch
// Initialize the sensor
Adafruit_TCS34725 tcs = Adafruit_TCS34725(
TCS34725_INTEGRATIONTIME_50MS,
TCS34725_GAIN_4X
);
void setup() {
Serial.begin(9600); // We use the serial monitor for debug
// RGB LED pins
pinMode(RED_PIN, OUTPUT);
pinMode(GREEN_PIN, OUTPUT);
pinMode(BLUE_PIN, OUTPUT);
// Sensor LED control pin
pinMode(SENSOR_LED_PIN, OUTPUT);
digitalWrite(SENSOR_LED_PIN, LOW); // turn off sensor LED initially
if (tcs.begin()) {
Serial.println("TCS34725 sensor found");
// Self-test only if sensor found: cycle RGB LED through R, G, B
for (int i = 7; i > 0; i--) {
// Red
Serial.println("RED Self Test");
analogWrite(RED_PIN, 255);
analogWrite(GREEN_PIN, 0);
analogWrite(BLUE_PIN, 0);
delay(50 * i);
// Green
Serial.println("GREEN Self Test");
analogWrite(RED_PIN, 0);
analogWrite(GREEN_PIN, 255);
analogWrite(BLUE_PIN, 0);
delay(50 * i);
// Blue
Serial.println("BLUE Self Test");
analogWrite(RED_PIN, 0);
analogWrite(GREEN_PIN, 0);
analogWrite(BLUE_PIN, 255);
delay(50 * i);
}
} else {
Serial.println("No TCS34725 sensor found ... check wiring?");
// RED LED to show error
analogWrite(RED_PIN, 155);
analogWrite(GREEN_PIN, 0);
analogWrite(BLUE_PIN, 0);
while (1);
}
}
void loop() {
uint16_t r, g, b, c;
tcs.getRawData(&r, &g, &b, &c);
if (c < 5) {
// In near total darkness: cycle through rainbow
showRainbowCycle();
} else {
// Normal color mimic
uint16_t maxRaw = max(max(r, g), b);
if (maxRaw == 0) maxRaw = 1;
int redVal = (uint32_t)r * 255 / maxRaw;
int greenVal = (uint32_t)g * 255 / maxRaw;
int blueVal = (uint32_t)b * 255 / maxRaw;
redVal = constrain(redVal, 0, 255);
greenVal = constrain(greenVal, 0, 255);
blueVal = constrain(blueVal, 0, 255);
analogWrite(RED_PIN, gammaCorrect(redVal));
analogWrite(GREEN_PIN, gammaCorrect(greenVal));
analogWrite(BLUE_PIN, gammaCorrect(blueVal));
}
delay(50); // smooth update
}
int gammaCorrect(int val) { // makes it look "better"
float gamma = 2.2;
return pow(val / 255.0, gamma) * 255.0;
}
void showRainbowCycle() { // If full dark gentle cycle thru colors
static float hue = 0;
hue += 0.5; // Change speed here
if (hue > 360) hue = 0;
float r, g, b;
float s = 1.0;
float v = 1.0;
float h = hue;
int i = int(h / 60.0) % 6;
float f = h / 60.0 - i;
float p = v * (1 - s);
float q = v * (1 - f * s);
float t = v * (1 - (1 - f) * s);
switch(i) {
case 0: r = v, g = t, b = p; break;
case 1: r = q, g = v, b = p; break;
case 2: r = p, g = v, b = t; break;
case 3: r = p, g = q, b = v; break;
case 4: r = t, g = p, b = v; break;
case 5: r = v, g = p, b = q; break;
}
analogWrite(RED_PIN, gammaCorrect(int(r * 255)));
analogWrite(GREEN_PIN, gammaCorrect(int(g * 255)));
analogWrite(BLUE_PIN, gammaCorrect(int(b * 255)));
}
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