DIYables ESP32 Web Apps Web Plotter
Overview
The WebPlotter example creates a real-time data visualization interface accessible through any web browser. Designed for ESP32 educational platform with enhanced data processing capabilities, real-time plotting features, and seamless integration with sensor monitoring systems. Perfect for visualizing sensor data, debugging algorithms, or monitoring system performance in real-time.
Watch this step-by-step video tutorial demonstrating how to use a DHT sensor with the Web Plotter app:
Features
- Real-time Data Plotting: Visualize sensor data as it streams from Arduino
- Multiple Data Series: Plot up to 8 different data streams simultaneously
- Auto-scaling: Automatic Y-axis scaling based on data range
- Interactive Interface: Zoom, pan, and analyze data trends
- WebSocket Communication: Instant updates with minimal latency
- Responsive Design: Works on desktop, tablet, and mobile devices
- Customizable Configuration: Adjustable plot titles, axis labels, and ranges
Hardware Used In This Tutorial
Or you can buy the following kits:
| 1 | × | DIYables ESP32 Starter Kit (ESP32 included) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
Disclosure: Some of the links in this section are Amazon affiliate links, meaning we may earn a commission at no additional cost to you if you make a purchase through them. Additionally, some links direct you to products from our own brand, DIYables .
Setup Instructions
Quick Instructions
Follow these instructions step by step:
- If this is your first time using the ESP32, refer to the tutorial on setting up the environment for ESP32 in the Arduino IDE.
- Connect the ESP32 board to your computer using a USB cable.
- Launch the Arduino IDE on your computer.
- Select the appropriate ESP32 board (e.g. ESP32 Dev Module) and COM port.
- Navigate to the Libraries icon on the left bar of the Arduino IDE.
- Search "DIYables ESP32 WebApps", then find the DIYables ESP32 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.
- On Arduino IDE, Go to File Examples DIYables ESP32 WebApps WebPlotter example, or copy the above code and paste it to the editor of Arduino IDE
/*
* DIYables WebApp Library - Web Plotter Example
*
* This example demonstrates the Web Plotter feature:
* - Real-time data visualization
* - Multiple data series support
* - Auto-scaling Y-axis
* - Responsive web interface
* - WebSocket communication for instant updates
*
* Hardware: ESP32 Boards
*
* Setup:
* 1. Update WiFi credentials below
* 2. Upload the sketch to your Arduino
* 3. Open Serial Monitor to see the IP address
* 4. Navigate to http://[IP_ADDRESS]/webplotter
*/
#include <DIYables_ESP32_Platform.h>
#include <DIYablesWebApps.h>
// WiFi credentials - UPDATE THESE WITH YOUR NETWORK
const char WIFI_SSID[] = "YOUR_WIFI_SSID";
const char WIFI_PASSWORD[] = "YOUR_WIFI_PASSWORD";
// Create WebApp server and page instances
ESP32ServerFactory serverFactory;
DIYablesWebAppServer webAppsServer(serverFactory, 80, 81);
DIYablesHomePage homePage;
DIYablesWebPlotterPage webPlotterPage;
// Simulation variables
unsigned long lastDataTime = 0;
const unsigned long DATA_INTERVAL = 1000; // Send data every 1000ms
float timeCounter = 0;
void setup() {
Serial.begin(9600);
delay(1000);
// TODO: Initialize your hardware pins and sensors here
Serial.println("DIYables ESP32 WebApp - Web Plotter Example");
// Add home and web plotter pages
webAppsServer.addApp(&homePage);
webAppsServer.addApp(&webPlotterPage);
// Optional: Add 404 page for better user experience
webAppsServer.setNotFoundPage(DIYablesNotFoundPage());
// Configure the plotter
webPlotterPage.setPlotTitle("Real-time Data Plotter");
webPlotterPage.setAxisLabels("Time (s)", "Values");
webPlotterPage.enableAutoScale(true);
webPlotterPage.setMaxSamples(50);
// Start the WebApp server
if (!webAppsServer.begin(WIFI_SSID, WIFI_PASSWORD)) {
while (1) {
Serial.println("Failed to start WebApp server!");
delay(1000);
}
}
// Set up callbacks
webPlotterPage.onPlotterDataRequest([]() {
Serial.println("Web client requested data");
sendSensorData();
});
Serial.println("\nWebPlotter is ready!");
Serial.println("Usage Instructions:");
Serial.println("1. Connect to the WiFi network");
Serial.println("2. Open your web browser");
Serial.println("3. Navigate to the Arduino's IP address");
Serial.println("4. Click on 'Web Plotter' to view real-time data");
Serial.println("\nGenerating simulated sensor data...");
}
void loop() {
// Handle web server and WebSocket connections
webAppsServer.loop();
// Send sensor data at regular intervals
if (millis() - lastDataTime >= DATA_INTERVAL) {
lastDataTime = millis();
sendSensorData();
timeCounter += DATA_INTERVAL / 1000.0; // Convert to seconds
}
}
void sendSensorData() {
// Generate simulated sensor data
// In a real application, replace these with actual sensor readings
// Simulated temperature sensor (sine wave with noise)
float temperature = 25.0 + 5.0 * sin(timeCounter * 0.5) + random(-100, 100) / 100.0;
// Simulated humidity sensor (cosine wave)
float humidity = 50.0 + 20.0 * cos(timeCounter * 0.3);
// Simulated light sensor (triangle wave)
float light = 512.0 + 300.0 * (2.0 * abs(fmod(timeCounter * 0.2, 2.0) - 1.0) - 1.0);
// Simulated analog pin reading
float analogValue = analogRead(A0);
// Send data using different methods:
// Method 1: Send individual values (uncomment to use)
// webPlotterPage.sendPlotData(temperature);
// Method 2: Send multiple values at once
webPlotterPage.sendPlotData(temperature, humidity, light / 10.0, analogValue / 100.0);
// Method 3: Send array of values (alternative approach)
// float values[] = {temperature, humidity, light / 10.0, analogValue / 100.0};
// webPlotterPage.sendPlotData(values, 4);
// Method 4: Send raw data string (for custom formatting)
// String dataLine = String(temperature, 2) + " " + String(humidity, 1) + " " + String(light / 10.0, 1);
// webPlotterPage.sendPlotData(dataLine);
// Print to Serial Monitor in Serial Plotter compatible format
// Format: Temperature Humidity Light Analog (tab-separated for Serial Plotter)
Serial.print(temperature, 1);
Serial.print("\t");
Serial.print(humidity, 1);
Serial.print("\t");
Serial.print(light / 10.0, 1);
Serial.print("\t");
Serial.println(analogValue / 100.0, 2);
}
- Configure WiFi credentials in the code by updating these lines:
const char WIFI_SSID[] = "YOUR_WIFI_NETWORK";
const char WIFI_PASSWORD[] = "YOUR_WIFI_PASSWORD";
- Click Upload button on Arduino IDE to upload code to ESP32
- Open the Serial Monitor
- Check out the result on Serial Monitor. It looks like the below
COM6
DIYables WebApp - Web Plotter Example
INFO: Added app /
INFO: Added app /web-plotter
DIYables WebApp Library
Platform: ESP32
Network connected!
IP address: 192.168.0.2
HTTP server started on port 80
Configuring WebSocket server callbacks...
WebSocket server started on port 81
WebSocket URL: ws://192.168.0.2:81
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/
📊 Web Plotter: http://192.168.0.2/web-plotter
==========================================
Autoscroll
Clear output
9600 baud
Newline
- If you do not see anything, reboot ESP32 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 like below image:
- Click to the Web Plotter link, you will see the Web Plotter app's UI like the below:
- Or you can also access the page directly by IP address followed by /web-plotter. For example: http://192.168.0.2/web-plotter
- Watch as the ESP32 generates simulated sensor data and plots it in real-time. You'll see multiple colored lines representing different data streams.
Creative Customization - Visualize Your Data Creatively
Transform the plotting interface to match your unique project requirements and create stunning data visualizations:
Data Source Configuration
Replace simulated data with real sensor readings:
Method 1: Single Sensor Reading
void sendTemperatureData() {
float temperature = analogRead(A0) * (5.0 / 1023.0) * 100; // LM35 temperature sensor
webPlotterPage.sendPlotData(temperature);
}
Method 2: Multiple Sensors
void sendMultipleSensors() {
float temperature = readTemperature();
float humidity = readHumidity();
float light = analogRead(A1) / 10.0;
float pressure = readPressure();
webPlotterPage.sendPlotData(temperature, humidity, light, pressure);
}
Method 3: Array of Values
void sendSensorArray() {
float sensors[6] = {
analogRead(A0) / 10.0, // Sensor 1
analogRead(A1) / 10.0, // Sensor 2
analogRead(A2) / 10.0, // Sensor 3
digitalRead(2) * 50, // Digital state
millis() / 1000.0, // Time counter
random(0, 100) // Random data
};
webPlotterPage.sendPlotData(sensors, 6);
}
Plot Customization
Custom Plot Appearance
void setupCustomPlot() {
webPlotterPage.setPlotTitle("Environmental Monitoring Station");
webPlotterPage.setAxisLabels("Time (minutes)", "Sensor Readings");
webPlotterPage.setYAxisRange(0, 100); // Fixed Y-axis range
webPlotterPage.setMaxSamples(100); // Show more data points
}
Dynamic Configuration
void setupDynamicPlot() {
webPlotterPage.setPlotTitle("Smart Garden Monitor");
webPlotterPage.setAxisLabels("Sample #", "Values");
webPlotterPage.enableAutoScale(true); // Auto-adjust Y-axis
// Configure callbacks for interactive features
webPlotterPage.onPlotterDataRequest([]() {
Serial.println("Client connected - sending initial data");
sendInitialDataBurst();
});
}
Advanced Data Processing
Moving Average Filter
float movingAverage(float newValue) {
static float readings[10];
static int index = 0;
static float total = 0;
total -= readings[index];
readings[index] = newValue;
total += readings[index];
index = (index + 1) % 10;
return total / 10.0;
}
void sendFilteredData() {
float rawValue = analogRead(A0);
float filteredValue = movingAverage(rawValue);
webPlotterPage.sendPlotData(rawValue / 10.0, filteredValue / 10.0);
}
Data Logging with Timestamps
void sendTimestampedData() {
unsigned long currentTime = millis() / 1000;
float sensorValue = analogRead(A0) / 10.0;
// Send time and value as separate data series
webPlotterPage.sendPlotData(currentTime, sensorValue);
// Also log to Serial for debugging
Serial.print("Time: ");
Serial.print(currentTime);
Serial.print("s, Value: ");
Serial.println(sensorValue);
}
Integration Examples
Environmental Monitoring
#include <DHT.h>
#define DHT_PIN 2
#define DHT_TYPE DHT22
DHT dht(DHT_PIN, DHT_TYPE);
void sendEnvironmentalData() {
float temperature = dht.readTemperature();
float humidity = dht.readHumidity();
float lightLevel = analogRead(A0) / 10.0;
if (!isnan(temperature) && !isnan(humidity)) {
webPlotterPage.sendPlotData(temperature, humidity, lightLevel);
Serial.print("T: ");
Serial.print(temperature);
Serial.print("°C, H: ");
Serial.print(humidity);
Serial.print("%, Light: ");
Serial.println(lightLevel);
}
}
Motor Control Feedback
void sendMotorData() {
int motorSpeed = analogRead(A0); // Speed potentiometer
int currentDraw = analogRead(A1); // Current sensor
int motorPosition = digitalRead(2); // Position sensor
float speedPercent = (motorSpeed / 1023.0) * 100;
float currentAmps = (currentDraw / 1023.0) * 5.0;
float positionDegrees = motorPosition * 90;
webPlotterPage.sendPlotData(speedPercent, currentAmps, positionDegrees);
}
PID Controller Visualization
float setpoint = 50.0;
float kp = 1.0, ki = 0.1, kd = 0.01;
float integral = 0, previousError = 0;
void sendPIDData() {
float input = analogRead(A0) / 10.0;
float error = setpoint - input;
integral += error;
float derivative = error - previousError;
float output = (kp * error) + (ki * integral) + (kd * derivative);
previousError = error;
// Plot setpoint, input, error, and output
webPlotterPage.sendPlotData(setpoint, input, error, output);
}
Performance Optimization
Efficient Data Transmission
unsigned long lastPlotUpdate = 0;
const unsigned long PLOT_INTERVAL = 100; // Update every 100ms
void efficientDataSending() {
if (millis() - lastPlotUpdate >= PLOT_INTERVAL) {
lastPlotUpdate = millis();
// Only send data at defined intervals
float value1 = analogRead(A0) / 10.0;
float value2 = analogRead(A1) / 10.0;
webPlotterPage.sendPlotData(value1, value2);
}
}
Conditional Data Sending
float lastSentValue = 0;
const float CHANGE_THRESHOLD = 5.0;
void sendOnChange() {
float currentValue = analogRead(A0) / 10.0;
// Only send if value changed significantly
if (abs(currentValue - lastSentValue) > CHANGE_THRESHOLD) {
webPlotterPage.sendPlotData(currentValue);
lastSentValue = currentValue;
}
}
Project Ideas
Scientific Applications
- Data Logger: Record temperature, humidity, pressure over time
- Vibration Analysis: Monitor accelerometer data for mechanical systems
- pH Monitoring: Track water quality in aquaponics systems
- Solar Panel Efficiency: Monitor voltage/current output vs. sunlight
Educational Projects
- Physics Experiments: Visualize pendulum motion, spring oscillations
- Chemistry Lab: Monitor reaction rates and temperature changes
- Biology Studies: Track plant growth sensors, environmental factors
- Mathematics: Plot mathematical functions and algorithmic outputs
Home Automation
- Energy Monitoring: Track power consumption patterns
- Garden Automation: Monitor soil moisture, light levels
- HVAC Control: Visualize temperature and humidity trends
- Security System: Plot motion sensor activities
Robotics and Control
- Robot Navigation: Plot position and orientation data
- Motor Control: Monitor speed, torque, and efficiency
- Sensor Fusion: Combine multiple sensor readings
- Path Planning: Visualize robot movement algorithms
Troubleshooting
Common Issues
1. No data appearing on plot
- Check WiFi connection status
- Verify WebSocket connection in browser console
- Ensure sendPlotData() is being called regularly
- Check Serial Monitor for error messages
2. Plot appears jumpy or erratic
- Implement data filtering (moving average)
- Reduce data sending frequency
- Check for sensor noise or connection issues
- Verify power supply stability
3. Browser performance issues
- Reduce maximum samples (setMaxSamples())
- Lower data transmission rate
- Close other browser tabs
- Use hardware acceleration in browser
4. WebSocket connection drops
- Check WiFi signal strength
- Verify router settings (firewall, port blocking)
- Implement reconnection logic in custom code
- Monitor ESP32 memory usage
Debug Tips
Enable Detailed Logging
void debugPlotterData() {
Serial.println("=== Plotter Debug Info ===");
Serial.print("Free RAM: ");
Serial.println(freeMemory());
Serial.print("Connected clients: ");
Serial.println(server.getConnectedClients());
Serial.print("Data rate: ");
Serial.println("Every " + String(DATA_INTERVAL) + "ms");
Serial.println("========================");
}
Test Data Generation
void generateTestPattern() {
static float phase = 0;
float sine = sin(phase) * 50 + 50;
float cosine = cos(phase) * 30 + 70;
float triangle = (phase / PI) * 25 + 25;
webPlotterPage.sendPlotData(sine, cosine, triangle);
phase += 0.1;
if (phase > 2 * PI) phase = 0;
}
Advanced Features
Custom Data Formatting
void sendFormattedData() {
float temp = 25.5;
float humidity = 60.3;
// Create custom formatted data string
String dataLine = String(temp, 1) + "\t" + String(humidity, 1);
webPlotterPage.sendPlotData(dataLine);
}
Integration with Other WebApps
void setupMultipleApps() {
// Add multiple web applications
server.addApp(new DIYablesHomePage());
server.addApp(new DIYablesWebDigitalPinsPage());
server.addApp(new DIYablesWebSliderPage());
server.addApp(&webPlotterPage);
server.addApp(new DIYablesNotFoundPage());
// Configure interactions between apps
webSliderPage.onSliderValueFromWeb([](int slider1, int slider2) {
// Use slider values to control what gets plotted
float scaleFactor = slider1 / 255.0;
// ... plotting logic
});
}
Real-time Control with Plotting
void controlAndPlot() {
// Read control inputs
int targetSpeed = analogRead(A0);
// Control hardware
analogWrite(9, targetSpeed / 4); // PWM output
// Read feedback
int actualSpeed = analogRead(A1);
int motorCurrent = analogRead(A2);
// Plot target vs actual
webPlotterPage.sendPlotData(
targetSpeed / 4.0, // Target speed
actualSpeed / 4.0, // Actual speed
motorCurrent / 10.0 // Current draw
);
}
ESP32 Web Plotter with DHT Sensor
The below is complete code for adapting this web app with a DHT11 sensor:
#include <DIYables_ESP32_Platform.h>
#include <DIYablesWebApps.h>
#include <DHT.h>
#define DHT_PIN 21
#define DHT_TYPE DHT11
DHT dht(DHT_PIN, DHT_TYPE);
// WiFi credentials - UPDATE THESE WITH YOUR NETWORK
const char WIFI_SSID[] = "YOUR_WIFI_SSID";
const char WIFI_PASSWORD[] = "YOUR_WIFI_PASSWORD";
// Create WebApp server and page instances
ESP32ServerFactory serverFactory;
DIYablesWebAppServer webAppsServer(serverFactory, 80, 81);
DIYablesHomePage homePage;
DIYablesWebPlotterPage webPlotterPage;
// Simulation variables
unsigned long lastDataTime = 0;
const unsigned long DATA_INTERVAL = 1000; // Send data every 1000ms
float timeCounter = 0;
void setup() {
Serial.begin(9600);
delay(1000);
// TODO: Initialize your hardware pins and sensors here
dht.begin();
Serial.println("DIYables ESP32 WebApp - Web Plotter Example");
// Add home and web plotter pages
webAppsServer.addApp(&homePage);
webAppsServer.addApp(&webPlotterPage);
// Optional: Add 404 page for better user experience
webAppsServer.setNotFoundPage(DIYablesNotFoundPage());
// Configure the plotter
webPlotterPage.setPlotTitle("Real-time Data Plotter");
webPlotterPage.setAxisLabels("Time (s)", "Values");
webPlotterPage.enableAutoScale(true);
webPlotterPage.setMaxSamples(50);
// Start the WebApp server
if (!webAppsServer.begin(WIFI_SSID, WIFI_PASSWORD)) {
while (1) {
Serial.println("Failed to start WebApp server!");
delay(1000);
}
}
// Set up callbacks
webPlotterPage.onPlotterDataRequest([]() {
Serial.println("Web client requested data");
sendSensorData();
});
Serial.println("\nWebPlotter is ready!");
Serial.println("Usage Instructions:");
Serial.println("1. Connect to the WiFi network");
Serial.println("2. Open your web browser");
Serial.println("3. Navigate to the Arduino's IP address");
Serial.println("4. Click on 'Web Plotter' to view real-time data");
Serial.println("\nGenerating simulated sensor data...");
}
void loop() {
// Handle web server and WebSocket connections
webAppsServer.loop();
// Send sensor data at regular intervals
if (millis() - lastDataTime >= DATA_INTERVAL) {
lastDataTime = millis();
sendSensorData();
timeCounter += DATA_INTERVAL / 1000.0; // Convert to seconds
}
delay(10000);
}
void sendSensorData() {
// Generate simulated sensor data
// In a real application, replace these with actual sensor readings
// Simulated temperature sensor (sine wave with noise)
float temperature = 25.0 + 5.0 * sin(timeCounter * 0.5) + random(-100, 100) / 100.0;
// Simulated humidity sensor (cosine wave)
float humidity = 50.0 + 20.0 * cos(timeCounter * 0.3);
// Simulated light sensor (triangle wave)
float light = 512.0 + 300.0 * (2.0 * abs(fmod(timeCounter * 0.2, 2.0) - 1.0) - 1.0);
// Simulated analog pin reading
float analogValue = analogRead(A0);
// Send data using different methods:
// Method 1: Send individual values (uncomment to use)
// webPlotterPage.sendPlotData(temperature);
// Method 2: Send multiple values at once
webPlotterPage.sendPlotData(temperature, humidity, light / 10.0, analogValue / 100.0);
// Method 3: Send array of values (alternative approach)
// float values[] = {temperature, humidity, light / 10.0, analogValue / 100.0};
// webPlotterPage.sendPlotData(values, 4);
// Method 4: Send raw data string (for custom formatting)
// String dataLine = String(temperature, 2) + " " + String(humidity, 1) + " " + String(light / 10.0, 1);
// webPlotterPage.sendPlotData(dataLine);
// Print to Serial Monitor in Serial Plotter compatible format
// Format: Temperature Humidity Light Analog (tab-separated for Serial Plotter)
Serial.print(temperature, 1);
Serial.print("\t");
Serial.print(humidity, 1);
Serial.print("\t");
Serial.print(light / 10.0, 1);
Serial.print("\t");
Serial.println(analogValue / 100.0, 2);
}
void sendEnvironmentalData() {
float temperature = dht.readTemperature();
float humidity = dht.readHumidity();
if (!isnan(temperature) && !isnan(humidity)) {
webPlotterPage.sendPlotData(temperature, humidity);
Serial.print("T: ");
Serial.print(temperature);
Serial.print("°C, H: ");
Serial.println(humidity);
}
}
The below is a step-by-step video tutorial demonstrating how to use a DHT sensor with the Web Plotter app:
Next Steps
After mastering the WebPlotter example, explore:
- MultipleWebApps - Combine plotting with control interfaces
- WebMonitor - Add debugging capabilities alongside plotting
- Custom Applications - Build your own specialized plotting tools
- Data Analysis - Implement statistical analysis of plotted data
Support
For additional help:
- Check the API Reference documentation
- Visit DIYables tutorials: https://esp32io.com/tutorials/diyables-esp32-webapps
- ESP32 community forums
- WebSocket debugging tools in browser developer console