Arduino Nano ESP32 - DIYables Bluetooth App Plotter
Overview
This example streams real-time data to the DIYables Bluetooth STEM app for live visualisation on the Arduino Nano ESP32 using BLE (Bluetooth Low Energy). Plot sensor readings, waveforms, and multi-channel data as live graphs on a smartphone. Suitable for data logging, signal analysis, sensor calibration, and scientific experiments.
Note: The Arduino Nano ESP32 supports BLE only — Classic Bluetooth is not supported. The DIYables Bluetooth App works on both Android and iOS with BLE.
Features
- Multi-Channel Plotting: Up to 6 data channels simultaneously
- Configurable Axes: Custom titles, labels, and Y-axis range
- Legend Labels: Name each data channel for clarity
- Sample Limit: Set maximum number of displayed samples
- Fast Streaming: Up to 10 updates per second (100 ms interval)
- Android & iOS Support: BLE is compatible with both platforms
- No Pairing Required: BLE connects without manual pairing
Hardware Preparation
Or you can buy the following kits:
| 1 | × | DIYables Sensor Kit (30 sensors/displays) | |
| 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 .
Arduino Nano ESP32 Code
Detailed Instructions
- New to the Arduino Nano ESP32? Start with the Arduino Nano ESP32 getting started guide.
- Connect the Arduino Nano ESP32 to your computer via USB.
- Open Arduino IDE.
- Select the Arduino Nano ESP32 board and the correct COM port.
- Click the Libraries icon in the left sidebar.
- Search for "DIYables Bluetooth" and select the DIYables Bluetooth library by DIYables.
- Click Install.
- When prompted to install dependencies, click Install All.
BLE Code
- In Arduino IDE, open File Examples DIYables Bluetooth ArduinoBLE_Plotter, or paste the code into the editor.
/*
* DIYables Bluetooth Library - ESP32 BLE Plotter Example
* Works with DIYables Bluetooth STEM app on Android and iOS
*
* This example demonstrates the Bluetooth Plotter feature:
* - Real-time data plotting via Bluetooth
* - Plot multiple data series simultaneously
* - Configurable plot settings
*
* Tutorial: https://diyables.io/bluetooth-app
* Author: DIYables
*/
#include <DIYables_BluetoothServer.h>
#include <DIYables_BluetoothPlotter.h>
#include <platforms/DIYables_Esp32BLE.h>
// BLE Configuration
const char* DEVICE_NAME = "ESP32BLE_Plotter";
const char* SERVICE_UUID = "19B10000-E8F2-537E-4F6C-D104768A1214";
const char* TX_UUID = "19B10001-E8F2-537E-4F6C-D104768A1214";
const char* RX_UUID = "19B10002-E8F2-537E-4F6C-D104768A1214";
// Create Bluetooth instances
DIYables_Esp32BLE bluetooth(DEVICE_NAME, SERVICE_UUID, TX_UUID, RX_UUID);
DIYables_BluetoothServer bluetoothServer(bluetooth);
// Create Plotter app instance
DIYables_BluetoothPlotter bluetoothPlotter;
// Variables for generating sample data
unsigned long lastPlotTime = 0;
const unsigned long PLOT_INTERVAL = 100;
float phase = 0;
void setup() {
Serial.begin(115200);
delay(1000);
Serial.println("DIYables Bluetooth - ESP32 BLE Plotter Example");
// Initialize Bluetooth server with platform-specific implementation
bluetoothServer.begin();
// Add plotter app to server
bluetoothServer.addApp(&bluetoothPlotter);
// Configure plotter settings
bluetoothPlotter.setPlotTitle("Sensor Data");
bluetoothPlotter.setAxisLabels("Time", "Value");
bluetoothPlotter.setYAxisRange(-15, 30);
bluetoothPlotter.setMaxSamples(100);
bluetoothPlotter.setLegendLabels("Sine", "Cosine", "Tangent");
// Set up connection event callbacks
bluetoothServer.setOnConnected([]() {
Serial.println("Bluetooth connected!");
});
bluetoothServer.setOnDisconnected([]() {
Serial.println("Bluetooth disconnected!");
});
bluetoothPlotter.onDataRequest([]() {
Serial.println("App requested plot data");
});
Serial.println("Waiting for Bluetooth connection...");
}
void loop() {
bluetoothServer.loop();
if (millis() - lastPlotTime >= PLOT_INTERVAL) {
lastPlotTime = millis();
float sine = sin(phase);
float cosine = cos(phase);
float tangent = tan(phase) * 0.3;
bluetoothPlotter.send(sine, cosine, tangent);
Serial.print(sine, 2);
Serial.print(" ");
Serial.print(cosine, 2);
Serial.print(" ");
Serial.println(tangent, 2);
phase += 0.1;
if (phase > 2 * PI) {
phase = 0;
}
}
delay(10);
}
- Click Upload to flash the sketch to the board.
- Open the Serial Monitor.
- The Serial Monitor output should look like:
COM6
DIYables Bluetooth - Plotter Example
Waiting for Bluetooth connection...
Autoscroll
Clear output
9600 baud
Newline
Mobile App
Note: The DIYables Bluetooth App works on both Android and iOS with BLE. No manual pairing is required.
- Launch the DIYables Bluetooth App.
- On first launch, grant the following permissions:
- Nearby Devices (Android 12+) / Bluetooth (iOS) — required to scan and connect to Bluetooth devices
- Location (Android 11 and below only) — required by older Android versions to scan for BLE
- Ensure Bluetooth is enabled on your device.
- Tap Connect on the home screen. The app will scan for BLE devices.
- Tap "Arduino_Plotter" in the scan results.
- After connecting, return to the home screen and open the Plotter app.
Tap the settings icon on the home screen to show or hide apps. See the DIYables Bluetooth App User Manual for details.
- A real-time plot of Sine, Cosine, and Tangent waveforms will appear.
Now look back at the Serial Monitor on Arduino IDE. You will see:
COM6
Bluetooth connected!
Sending plot data...
Sine: 0.00, Cosine: 10.00, Tangent: 0.00
Autoscroll
Clear output
9600 baud
Newline
Creative Customization - Adapt the Code to Your Project
Configure Plot Appearance
// Set plot title
bluetoothPlotter.setPlotTitle("My Sensor Data");
// Set axis labels
bluetoothPlotter.setAxisLabels("Time", "Value");
// Set Y-axis range
bluetoothPlotter.setYAxisRange(-100, 100);
// Set maximum samples to display
bluetoothPlotter.setMaxSamples(200);
// Set legend labels for each channel
bluetoothPlotter.setLegendLabels("Temperature", "Humidity", "Pressure");
Send Data Points
// Send a single value
bluetoothPlotter.send(sensorValue);
// Send two values
bluetoothPlotter.send(temperature, humidity);
// Send three values
bluetoothPlotter.send(value1, value2, value3);
// Send up to six values
bluetoothPlotter.send(ch1, ch2, ch3, ch4, ch5, ch6);
Handle Data Request
bluetoothPlotter.onDataRequest([]() {
Serial.println("App requested data");
// App just connected or needs initial config
});
Programming Examples
Temperature and Humidity Logger
DIYables_BluetoothPlotter bluetoothPlotter(bluetoothServer);
void setup() {
bluetoothPlotter.setPlotTitle("Environment Monitor");
bluetoothPlotter.setAxisLabels("Time", "Value");
bluetoothPlotter.setYAxisRange(0, 100);
bluetoothPlotter.setMaxSamples(100);
bluetoothPlotter.setLegendLabels("Temp (°C)", "Humidity (%)");
}
void loop() {
bluetoothServer.loop();
static unsigned long lastTime = 0;
if (millis() - lastTime >= 1000) {
lastTime = millis();
float temp = readTemperature();
float humidity = readHumidity();
bluetoothPlotter.send(temp, humidity);
}
}
Analog Input Plotter
void loop() {
bluetoothServer.loop();
static unsigned long lastTime = 0;
if (millis() - lastTime >= 100) {
lastTime = millis();
int a0 = analogRead(A0);
int a1 = analogRead(A1);
int a2 = analogRead(A2);
bluetoothPlotter.send(a0, a1, a2);
}
}
Troubleshooting
Common Issues
1. Device not visible in the app
- Confirm the board is powered on and the sketch is uploaded
- Verify Bluetooth is enabled on your phone
- On Android 11 and below, enable Location services as well
2. Plot not updating
- Verify data is sent inside loop()
- Confirm bluetoothServer.loop() is called
- Ensure the app is on the Plotter screen
3. Data looks incorrect or noisy
- Check sensor wiring and readings
- Confirm the Y-axis range matches your data range
- Consider applying smoothing or filtering to the data
4. Plot title or labels not appearing
- Set the plot configuration in setup() before a connection is made
- Use the onDataRequest callback to re-send configuration when needed
5. Upload fails or board not recognized
- Install the latest Arduino Nano ESP32 board package via Board Manager
- Try a different USB cable or port
Project Ideas
- Environmental monitoring (temperature, humidity, pressure)
- Accelerometer/gyroscope data visualization
- Analog sensor calibration tool
- Signal analysis and comparison
- Science experiment data logger
Next Steps
After completing the Bluetooth Plotter example, explore:
- Bluetooth Table — Structured data display
- Bluetooth Monitor — Text-based data output
- Bluetooth Temperature — Gauge-style temperature display
- Multiple Bluetooth Apps — Combine plotter with other app widgets
Support
For additional help:
- Check the API Reference documentation
- Visit DIYables tutorials
- Arduino community forums