Arduino UNO R4 - Color Sensor via Web
This fun project combines the TCS3200D/TCS230 color sensor with a web-based Minion character. The Arduino UNO R4 WiFi reads colors from the sensor and sends the detected color to a web browser via WebSocket. The Minion on the web page changes its skin color in real-time to match whatever color you put in front of the sensor! To make it easy to build the web interface and handle real-time communication, we will use the DIYables WebApps library.
- The Arduino UNO R4 reads RGB values from the TCS3200D/TCS230 color sensor
- The Arduino converts the RGB values to a HEX color code
- The color code is sent to a web browser via WebSocket in real-time
- The web page displays a fun animated Minion whose body, arms, and eyelids change color
We also provide a step-by-step video instruction at the bottom of this tutorial.
Hardware Preparation
Or you can buy the following kits:
| 1 | × | DIYables STEM V4 IoT Starter Kit (Arduino included) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables .
Additionally, some of these links are for products from our own brand, DIYables .
Overview of TCS3200D/TCS230 Color Sensor and DIYables WebApps
Learn about the TCS3200D/TCS230 color sensor, DIYables WebApps library, and how to create custom web apps in the tutorials below:
Wiring Diagram
This image shows how to connect the TCS3200 color sensor to Arduino UNO R4 WiFi:
| TCS3200 Color Sensor | Arduino UNO R4 |
|---|---|
| VCC | 5V |
| GND | GND |
| S0 | Pin 4 |
| S1 | Pin 3 |
| S2 | Pin 6 |
| S3 | Pin 5 |
| OUT | Pin 7 |
This image is created using Fritzing. Click to enlarge image
See The best way to supply power to the Arduino Uno R4 and other components.
How It Works
- The Arduino reads the color sensor every 1 second.
- For each reading, it selects the red, green, and blue filters one at a time using the S2/S3 pins, then measures the pulse width on the OUT pin.
- The raw pulse width values are mapped to 0-255 RGB values using calibration values (from the calibration step).
- The RGB values are converted to a HEX color string (e.g., #FF8000).
- The HEX color string is sent to the web browser via WebSocket using the DIYables WebApps library.
- The web page receives the color and updates the Minion's body, arms, and eyelids to that color in real-time.
Arduino UNO R4 Code - Color Sensor Minion Web App
The code consists of 4 files:
- ColorSensor.ino - Main Arduino sketch: reads the color sensor and sends the color to the web page
- CustomWebApp.h - Header file: defines the custom web app page class
- CustomWebApp.cpp - Implementation file: handles WebSocket communication with the "Color Sensor:" identifier
- custom_page_html.h - Web page: contains the animated Minion HTML/CSS/JavaScript that receives colors and updates the Minion's skin
ColorSensor.ino
/*
* This Arduino UNO R4 code was developed by newbiely.com
*
* This Arduino UNO R4 code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-uno-r4/arduino-uno-r4-color-sensor-via-web
*/
#include <DIYablesWebApps.h>
#include "CustomWebApp.h"
// CHANGE THESE TO YOUR WIFI DETAILS
const char WIFI_SSID[] = "YOUR_WIFI_SSID";
const char WIFI_PASSWORD[] = "YOUR_WIFI_PASSWORD";
int status = WL_IDLE_STATUS;
// TCS3200 Pins
const int S0 = 4, S1 = 3, S2 = 6, S3 = 5, sensorOut = 7;
UnoR4ServerFactory serverFactory;
DIYablesWebAppServer webAppsServer(serverFactory, 80, 81);
DIYablesHomePage homePage;
CustomWebAppPage customPage;
unsigned long lastColorRead = 0;
void setup() {
Serial.begin(9600);
// Initialize TCS3200 pins
pinMode(S0, OUTPUT);
pinMode(S1, OUTPUT);
pinMode(S2, OUTPUT);
pinMode(S3, OUTPUT);
pinMode(sensorOut, INPUT);
digitalWrite(S0, HIGH);
digitalWrite(S1, LOW); // 20% frequency scaling
webAppsServer.addApp(&homePage);
webAppsServer.addApp(&customPage);
// Check for the WiFi module
if (WiFi.status() == WL_NO_MODULE) {
Serial.println("Communication with WiFi module failed!");
// Stop program execution
while (true);
}
String fv = WiFi.firmwareVersion();
if (fv < WIFI_FIRMWARE_LATEST_VERSION) {
Serial.println("Please upgrade the firmware");
}
// Attempt to connect to WiFi network
while (status != WL_CONNECTED) {
// Connect to WPA/WPA2 network (change if using open or WEP)
status = WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
// Wait 10 seconds for connection
delay(10000);
}
webAppsServer.begin();
Serial.println("Color Web Server Ready!");
}
void loop() {
webAppsServer.loop();
// Read color every 1 second
if (millis() - lastColorRead > 1000) {
// Read Red color
digitalWrite(S2, LOW);
digitalWrite(S3, LOW);
int r = map(pulseIn(sensorOut, LOW), 31, 150, 255, 0);
// Read Green color
digitalWrite(S2, HIGH);
digitalWrite(S3, HIGH);
int g = map(pulseIn(sensorOut, LOW), 35, 180, 255, 0);
// Read Blue color
digitalWrite(S2, LOW);
digitalWrite(S3, HIGH);
int b = map(pulseIn(sensorOut, LOW), 30, 150, 255, 0);
// Convert to HEX and send to Web
char hexColor[8];
sprintf(hexColor, "#%02X%02X%02X", constrain(r, 0, 255), constrain(g, 0, 255), constrain(b, 0, 255));
customPage.sendToWeb(String(hexColor));
Serial.println("Sent to Minion: " + String(hexColor));
lastColorRead = millis();
}
}
CustomWebApp.h
/*
* This Arduino UNO R4 code was developed by newbiely.com
*
* This Arduino UNO R4 code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-uno-r4/arduino-uno-r4-color-sensor-via-web
*/
#ifndef CUSTOM_WEBAPP_H
#define CUSTOM_WEBAPP_H
#include <DIYablesWebApps.h>
/**
* Simple Custom WebApp Page
*
* This is a template for creating your own custom web applications.
* It provides basic controls like buttons and sliders that communicate
* with your Arduino in real-time.
*/
class CustomWebAppPage : public DIYablesWebAppPageBase {
private:
// WebSocket message identifier for this custom app
static const String APP_IDENTIFIER;
public:
CustomWebAppPage();
// ========================================
// REQUIRED METHODS - USED BY LIBRARY - DON'T CHANGE THESE!
// ========================================
void handleHTTPRequest(IWebClient& client) override;
void handleWebSocketMessage(IWebSocket& ws, const char* message, uint16_t length) override;
const char* getPageInfo() const override;
String getNavigationInfo() const override;
// ========================================
// YOUR METHODS - USE THESE IN YOUR CODE!
// ========================================
void onCustomMessageReceived(void (*callback)(const String& payload));
void sendToWeb(const String& message);
};
#endif
CustomWebApp.cpp
/*
* This Arduino UNO R4 code was developed by newbiely.com
*
* This Arduino UNO R4 code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-uno-r4/arduino-uno-r4-color-sensor-via-web
*/
#include "CustomWebApp.h"
#include "custom_page_html.h"
// Define the static member - WebSocket message identifier for this custom app
const String CustomWebAppPage::APP_IDENTIFIER = "Color Sensor:";
// Callback function for handling messages from web browser
void (*customMessageCallback)(const String& payload) = nullptr;
CustomWebAppPage::CustomWebAppPage() : DIYablesWebAppPageBase("/custom") {
}
void CustomWebAppPage::handleHTTPRequest(IWebClient& client) {
// Send the HTML page to web browser
sendHTTPHeader(client);
client.print(CUSTOM_PAGE_HTML);
}
void CustomWebAppPage::handleWebSocketMessage(IWebSocket& ws, const char* message, uint16_t length) {
String messageStr = String(message, length);
Serial.print("Color Sensor WebApp received: ");
Serial.println(messageStr);
// Only handle messages that start with our app identifier
if (messageStr.startsWith(APP_IDENTIFIER)) {
String payload = messageStr.substring(APP_IDENTIFIER.length()); // Remove identifier
// Call your callback function with the payload
if (customMessageCallback) {
customMessageCallback(payload);
}
}
}
void CustomWebAppPage::onCustomMessageReceived(void (*callback)(const String& payload)) {
customMessageCallback = callback;
}
void CustomWebAppPage::sendToWeb(const String& message) {
// Send message to web browser with app identifier
String fullMessage = APP_IDENTIFIER + message;
broadcastToAllClients(fullMessage.c_str());
}
const char* CustomWebAppPage::getPageInfo() const {
return "🔧 Color Sensor WebApp";
}
String CustomWebAppPage::getNavigationInfo() const {
String result = "<a href=\"";
result += getPagePath();
result += "\" class=\"app-card custom\" style=\"background: linear-gradient(135deg, #007bff 0%, #0056b3 100%);\">";
result += "<h3>🔧 Color Sensor WebApp</h3>";
result += "<p>Simple template for your own apps</p>";
result += "</a>";
return result;
}
custom_page_html.h
/*
* This Arduino UNO R4 code was developed by newbiely.com
*
* This Arduino UNO R4 code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-uno-r4/arduino-uno-r4-color-sensor-via-web
*/
#ifndef CUSTOM_PAGE_HTML_H
#define CUSTOM_PAGE_HTML_H
const char CUSTOM_PAGE_HTML[] PROGMEM = R"HTML_WRAPPER(
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
<title>Mobile Laughing Minion</title>
<style>
body { margin: 0; padding: 20px; box-sizing: border-box; display: flex; flex-direction: column; justify-content: flex-start; align-items: center; background-color: #f0f8ff; font-family: sans-serif; overflow-x: hidden; }
.text { font-size: clamp(16px, 5vw, 24px); font-weight: bold; color: #333; margin-bottom: 20px; text-align: center; z-index: 10; }
.scale-wrapper { transform-origin: top center; display: flex; justify-content: center; align-items: flex-start; }
.minion-container { position: relative; width: 200px; height: 400px; }
.body { position: absolute; top: 20px; left: 25px; width: 150px; height: 300px; background-color: #FFD90F; border-radius: 75px; box-shadow: inset -10px -10px 20px rgba(0,0,0,0.1); overflow: hidden; z-index: 2; transition: background-color 0.5s; }
.overalls { position: absolute; bottom: 0; width: 100%; height: 90px; background-color: #225A94; border-radius: 0 0 75px 75px; box-shadow: inset -10px -10px 20px rgba(0,0,0,0.2); }
.pocket { position: absolute; bottom: 30px; left: 50px; width: 50px; height: 40px; background-color: #1A4674; border-radius: 10px 10px 20px 20px; border: 2px dashed #fce144; }
.strap { position: absolute; top: 65px; left: 0; width: 100%; height: 25px; background-color: #333; z-index: 1; }
.goggles-wrapper { position: absolute; top: 50px; left: -5px; width: 160px; display: flex; justify-content: center; z-index: 3; }
.goggle { position: relative; width: 50px; height: 50px; background-color: white; border: 12px solid #999; border-radius: 50%; box-shadow: 3px 3px 8px rgba(0,0,0,0.2), inset 3px 3px 8px rgba(0,0,0,0.1); margin: 0 -2px; overflow: hidden; }
.pupil { position: absolute; top: 50%; left: 50%; width: 20px; height: 20px; background-color: #4B3621; border-radius: 50%; transform: translate(-50%, -50%); transition: transform 0.2s ease-out; }
.pupil::after { content: ''; position: absolute; top: 4px; left: 4px; width: 6px; height: 6px; background-color: black; border-radius: 50%; }
.catchlight { position: absolute; top: 2px; right: 4px; width: 4px; height: 4px; background-color: white; border-radius: 50%; z-index: 4; }
.eyelid { position: absolute; top: 0; left: 0; width: 100%; height: 100%; background-color: #FFD90F; border-bottom: 3px solid #D4B200; transform-origin: top; transform: scaleY(0); z-index: 5; animation: blink 4s infinite; }
.mouth { position: absolute; top: 145px; left: 35px; width: 80px; height: 45px; background-color: #3E2723; border-radius: 10px 10px 60px 60px; overflow: hidden; z-index: 3; box-shadow: inset 0 5px 10px rgba(0,0,0,0.5); animation: laugh 0.2s infinite alternate ease-in-out; }
.teeth { position: absolute; top: 0; left: 0; width: 100%; height: 14px; background-color: #fff; border-radius: 0 0 5px 5px; }
.tongue { position: absolute; bottom: -5px; left: 20px; width: 40px; height: 25px; background-color: #FF5252; border-radius: 50%; animation: wag 0.2s infinite alternate ease-in-out; }
.arm { position: absolute; top: 140px; width: 25px; height: 80px; background-color: #FFD90F; border-radius: 12px; z-index: 1; transition: background-color 0.5s; }
.arm.left { left: 10px; transform: rotate(35deg); }
.arm.right { right: 15px; transform: rotate(-35deg); }
.glove { position: absolute; bottom: -15px; left: -5px; width: 35px; height: 35px; background-color: #333; border-radius: 50%; }
.leg { position: absolute; bottom: 50px; width: 25px; height: 40px; background-color: #225A94; z-index: 1; }
.leg.left { left: 60px; }
.leg.right { left: 115px; }
.shoe { position: absolute; bottom: -15px; left: -10px; width: 45px; height: 20px; background-color: #222; border-radius: 20px 20px 5px 5px; border-bottom: 5px solid #111; }
@keyframes blink { 0%, 94%, 100% { transform: scaleY(0); } 97% { transform: scaleY(1); } }
@keyframes laugh { 0% { height: 40px; transform: scaleX(1); } 100% { height: 55px; transform: scaleX(1.05); } }
@keyframes wag { 0% { transform: translateY(0); } 100% { transform: translateY(-3px); } }
</style>
</head>
<body>
<div class="text" id="status-text">Just watch him look around! 👀</div>
<div class="scale-wrapper" id="minionWrapper">
<div class="minion-container">
<div class="arm left" id="armL"><div class="glove"></div></div>
<div class="arm right" id="armR"><div class="glove"></div></div>
<div class="leg left"><div class="shoe"></div></div>
<div class="leg right"><div class="shoe"></div></div>
<div class="body" id="minionBody">
<div class="overalls">
<div class="pocket"></div>
</div>
<div class="strap"></div>
<div class="goggles-wrapper">
<div class="goggle"><div class="pupil"><div class="catchlight"></div></div><div class="eyelid" id="eyelidL"></div></div>
<div class="goggle"><div class="pupil"><div class="catchlight"></div></div><div class="eyelid" id="eyelidR"></div></div>
</div>
<div class="mouth">
<div class="teeth"></div>
<div class="tongue"></div>
</div>
</div>
</div>
</div>
<script>
const APP_IDENTIFIER = 'Color Sensor:';
let ws = null;
function connectWebSocket() {
ws = new WebSocket('ws://' + location.hostname + ':81');
ws.onopen = () => document.getElementById('status-text').textContent = "Arduino Uno R4 - Color Sensor";
ws.onclose = () => setTimeout(connectWebSocket, 2000);
ws.onmessage = (event) => {
if (event.data.startsWith(APP_IDENTIFIER)) {
let color = event.data.substring(APP_IDENTIFIER.length);
// Cập nhật màu cho thân, tay và mí mắt
document.getElementById('minionBody').style.backgroundColor = color;
document.getElementById('armL').style.backgroundColor = color;
document.getElementById('armR').style.backgroundColor = color;
document.getElementById('eyelidL').style.backgroundColor = color;
document.getElementById('eyelidR').style.backgroundColor = color;
document.getElementById('status-text').style.color = color;
}
};
}
function resizeMinion() {
const wrapper = document.getElementById('minionWrapper');
const availableWidth = window.innerWidth - 40;
const minionTrueWidth = 260;
const minionHeight = 400;
let scaleFactor = availableWidth / minionTrueWidth;
if (scaleFactor > 1.5) scaleFactor = 1.5;
wrapper.style.transform = `scale(${scaleFactor})`;
wrapper.style.height = `${minionHeight * scaleFactor}px`;
}
window.addEventListener('resize', resizeMinion);
resizeMinion();
connectWebSocket();
const pupils = document.querySelectorAll('.pupil');
function moveEyesAutomatically() {
const angle = Math.random() * Math.PI * 2;
const distance = Math.random() * 15;
const pupilX = Math.cos(angle) * distance;
const pupilY = Math.sin(angle) * distance;
pupils.forEach(pupil => {
pupil.style.transform = `translate(calc(-50% + ${pupilX}px), calc(-50% + ${pupilY}px))`;
});
}
setInterval(moveEyesAutomatically, 600);
</script>
</body>
</html>
)HTML_WRAPPER";
#endif
Detailed Instructions
Follow these instructions step by step:
- If this is your first time using the Arduino Uno R4 WiFi, refer to the tutorial on setting up the environment for Arduino Uno R4 WiFi in the Arduino IDE.
- Calibrate your color sensor first by following the TCS3200D/TCS230 calibration guide. Note down your calibration values (redMin, redMax, greenMin, greenMax, blueMin, blueMax).
- Wire the components according to the wiring diagram above.
- Connect the Arduino Uno R4 WiFi board to your computer using a USB cable.
- Launch the Arduino IDE on your computer.
- Select the appropriate Arduino Uno R4 board (e.g., Arduino Uno R4 WiFi) and COM port.
- Navigate to the Libraries icon on the left bar of the Arduino IDE.
- Search "DIYables WebApps", then find the DIYables WebApps library by DIYables.
- Click Install button to install the library.
- You will be asked for installing some other library dependencies.
- Click Install All button to install all library dependencies.
- Create a new sketch in Arduino IDE and name it ColorSensor.
- Copy and paste all 4 files above into the Arduino IDE project. The Arduino IDE project should have 4 files as shown below:
- In the ColorSensor.ino file, update the Wi-Fi details (SSID and password) with your own:
const char WIFI_SSID[] = "YOUR_WIFI_NAME";
const char WIFI_PASSWORD[] = "YOUR_WIFI_PASSWORD";
- Update the calibration values in the map() calls inside loop() with your own calibration values from the calibration step. For example, if your calibration gave you redMin = 42, redMax = 210, greenMin = 55, greenMax = 185, blueMin = 60, blueMax = 172, change the lines to:
int r = map(pulseIn(sensorOut, LOW), 42, 210, 255, 0);
int g = map(pulseIn(sensorOut, LOW), 55, 185, 255, 0);
int b = map(pulseIn(sensorOut, LOW), 60, 172, 255, 0);
- Click the Upload button in Arduino IDE to upload the code to Arduino UNO R4.
- Open the Serial Monitor. You will see output like this:
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Uno R4 WiFi' on 'COM15')
New Line
9600 baud
Color Web Server Ready!
INFO: Added app /
INFO: Added app /custom
DIYables WebApp Library
Platform: Arduino Uno R4 WiFi
Network connected!
IP address: 192.168.0.2
HTTP server started on port 80
WebSocket server started on port 81
==========================================
DIYables WebApp Ready!
==========================================
📱 Web Interface: http://192.168.0.2
🔗 WebSocket: ws://192.168.0.2:81
📋 Available Applications:
🏠 Home Page: http://192.168.0.2/
🔧 Color Sensor WebApp: http://192.168.0.2/custom
==========================================
Sent to Minion: #FFD200
Sent to Minion: #00C832
Sent to Minion: #0028FF
- If you do not see anything, reboot the Arduino board.
- Take note of the IP address displayed, and enter this address into the address bar of a web browser on your smartphone or PC.
- Example: http://192.168.0.2
- You will see the home page. Click the Color Sensor WebApp link.
- Or you can access the Minion page directly by IP address followed by /custom. For example: http://192.168.0.2/custom
- You will see the animated Minion character on the web page.
- Place a colored object in front of the TCS3200 sensor — the Minion's skin color will change in real-time to match the detected color!
You can see the step-by-step instructions in the video below.
How the Code Works
Arduino Side (ColorSensor.ino)
The main sketch does the following:
- Initializes the TCS3200 sensor pins: S0, S1 are set for 20% frequency scaling. S2, S3 are used to select color filters.
- Reads color every 1 second: In the loop(), the Arduino selects the red, green, and blue filters one by one, reads the pulse width using pulseIn(), and maps the raw values to 0-255 RGB values using your calibration numbers.
- Converts to HEX: The RGB values are formatted into a HEX color string like #FF8000 using sprintf().
- Sends to web browser: The HEX string is sent to all connected web clients via customPage.sendToWeb().
Web Page Side (custom_page_html.h)
The HTML page contains:
- An animated Minion character built entirely with CSS — including blinking eyes, a laughing mouth, and randomly moving pupils.
- WebSocket connection: The JavaScript connects to the Arduino's WebSocket server (port 81) and listens for incoming color messages.
- Color update: When a message like #FF8000 is received, the Minion's body, arms, and eyelids smoothly transition to the new color using CSS transition.
- Auto-reconnect: If the WebSocket connection drops, the page automatically tries to reconnect every 2 seconds.
- Responsive design: The Minion scales automatically to fit different screen sizes (phones, tablets, desktops).
Communication Protocol
This project uses the DIYables WebApps custom web app framework with the identifier "Color Sensor:":
- Arduino sends: Color Sensor:#FF8000 (identifier + HEX color)
- Web page receives: Strips the identifier and applies the remaining HEX color #FF8000 to the Minion
For more details about the communication protocol and how to customize the web app, see the DIYables WebApps Custom WebApp tutorial.