Arduino UNO R4 - DIYables Bluetooth App Plotter
Overview
The Bluetooth Plotter example streams real-time data to the DIYables Bluetooth STEM app for live visualization. Designed for Arduino UNO R4 WiFi using BLE (Bluetooth Low Energy) plot sensor readings, waveforms, and multi-channel data as real-time graphs on your smartphone. Ideal for data logging, signal analysis, sensor calibration, and science experiments.
Note: The Arduino UNO R4 WiFi only supports BLE (Bluetooth Low Energy). It does not support Classic Bluetooth. The DIYables Bluetooth App supports both BLE and Classic Bluetooth on Android, and BLE on iOS. Since this board uses BLE, the app works on both Android and iOS.
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 samples to display
- Fast Streaming: Up to 10 updates per second (100ms interval)
- Works on Android & iOS: BLE is supported on both platforms
- No Pairing Required: BLE auto-connects without manual pairing
Hardware Preparation
Or you can buy the following kits:
| 1 | × | DIYables STEM V4 IoT Starter Kit (Arduino included) | |
| 1 | × | DIYables Sensor Kit (30 sensors/displays) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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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 UNO R4 WiFi Code
Detailed Instructions
Follow these instructions step by step:
- If this is your first time using the Arduino UNO R4 WiFi, refer to the Arduino UNO R4 WiFi getting started guide.
- Connect the Arduino UNO R4 WiFi board to your computer using a USB cable.
- Launch the Arduino IDE on your computer.
- Select Arduino UNO R4 WiFi board and the appropriate COM port.
- Navigate to the Libraries icon on the left bar of the Arduino IDE.
- Search "DIYables Bluetooth", then find the DIYables Bluetooth 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.
BLE Code
- On Arduino IDE, Go to File Examples DIYables Bluetooth ArduinoBLE_Plotter example, or copy the above code and paste it to the editor of Arduino IDE
/*
* DIYables Bluetooth Library - Bluetooth 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
*
* Compatible Boards:
* - Arduino UNO R4 WiFi
* - Arduino Nano 33 BLE / BLE Sense
* - Arduino Nano 33 IoT
* - Arduino MKR WiFi 1010
* - Arduino Nano RP2040 Connect
* - Any board supporting the ArduinoBLE library
*
* Setup:
* 1. Upload the sketch to your Arduino
* 2. Open Serial Monitor to see connection status
* 3. Use DIYables Bluetooth App to connect and view the plot
*
* Tutorial: https://diyables.io/bluetooth-app
* Author: DIYables
*/
#include <DIYables_BluetoothServer.h>
#include <DIYables_BluetoothPlotter.h>
#include <platforms/DIYables_ArduinoBLE.h>
// BLE Configuration
const char* DEVICE_NAME = "Arduino_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_ArduinoBLE 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; // Plot every 100ms
float phase = 0;
void setup() {
Serial.begin(9600);
while (!Serial);
Serial.println("DIYables Bluetooth - 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); // Fixed range
bluetoothPlotter.setMaxSamples(100); // Show last 100 samples
bluetoothPlotter.setLegendLabels("Sine", "Cosine", "Tangent"); // Custom legend labels
// Uncomment to enable auto-scaling instead of fixed range:
// bluetoothPlotter.enableAutoScale(true);
// Set up connection event callbacks
bluetoothServer.setOnConnected([]() {
Serial.println("Bluetooth connected!");
});
bluetoothServer.setOnDisconnected([]() {
Serial.println("Bluetooth disconnected!");
});
// Optional: Handle requests for current plot data (when app loads)
bluetoothPlotter.onDataRequest([]() {
// Send initial data when app requests it
Serial.println("App requested plot data");
// Could send recent historical data here if needed
});
Serial.println("Waiting for Bluetooth connection...");
}
void loop() {
// Handle Bluetooth server communications
bluetoothServer.loop();
// Send plot data at regular intervals
if (millis() - lastPlotTime >= PLOT_INTERVAL) {
lastPlotTime = millis();
// Generate sample data (sine and cosine waves)
float sine = sin(phase);
float cosine = cos(phase);
float tangent = tan(phase) * 0.3; // Scaled down
// Send data to Bluetooth plotter (multiple series)
// You can send 1 to 4 values, or use array for more
bluetoothPlotter.send(sine, cosine, tangent);
// Also print to Serial for Arduino IDE Serial Plotter comparison
// Format: value1 value2 value3 (space-separated for Serial Plotter)
Serial.print(sine, 2);
Serial.print(" ");
Serial.print(cosine, 2);
Serial.print(" ");
Serial.println(tangent, 2);
// Alternative methods:
// bluetoothPlotter.send(sine); // Single value
// bluetoothPlotter.send(sine, cosine); // Two values
// float values[] = {sine, cosine, tangent};
// bluetoothPlotter.send(values, 3); // Array of values
phase += 0.1;
if (phase > 2 * PI) {
phase = 0;
}
// TODO: Replace sample data with your actual sensor readings
// Examples:
// - Temperature sensor: bluetoothPlotter.send(temperature);
// - Accelerometer: bluetoothPlotter.send(accelX, accelY, accelZ);
// - Multiple sensors: bluetoothPlotter.send(sensor1, sensor2, sensor3);
}
delay(10);
}
- Click Upload button on Arduino IDE to upload code to Arduino UNO R4 WiFi
- Open the Serial Monitor
- Check out the result on Serial Monitor. It looks like the below:
COM6
DIYables Bluetooth - Plotter Example
Waiting for Bluetooth connection...
Autoscroll
Clear output
9600 baud
Newline
Mobile App
Note: The DIYables Bluetooth App supports both BLE and Classic Bluetooth on Android, and BLE on iOS. Since the Arduino UNO R4 WiFi uses BLE, the app works on both Android and iOS. No manual pairing is needed for BLE — just scan and connect.
- Open the DIYables Bluetooth App
- When opening the app for the first time, it will ask for permissions. Please grant the following:
- Nearby Devices permission (Android 12+) / Bluetooth permission (iOS) - required to scan and connect to Bluetooth devices
- Location permission (Android 11 and below only) - required by older Android versions to scan for BLE devices
- Make sure Bluetooth is turned on on your phone
- On the home screen, tap the Connect button. The app will scan for BLE devices.
- Find and tap "Arduino_Plotter" in the scan results to connect.
- Once connected, the app automatically goes back to the home screen. Select the Plotter app from the app menu.
Note: You can tap the settings icon on the home screen to hide/show apps on the home screen. For more details, see the DIYables Bluetooth App User Manual.
- You will see a real-time plot of Sine, Cosine, and Tangent waveforms
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. Cannot find the device in the app
- Make sure the Arduino UNO R4 WiFi is powered on and the sketch is uploaded
- Ensure your phone's Bluetooth is enabled
- On Android 11 and below, also enable Location services
2. Plot not updating
- Verify data is being sent in the loop() function
- Check that bluetoothServer.loop() is called
- Ensure the app is on the Plotter screen
3. Data looks wrong or noisy
- Check sensor wiring and readings
- Verify Y-axis range matches your data range
- Consider adding data smoothing/filtering
4. Plot title or labels not appearing
- Set plot configuration in setup() before connecting
- Make sure onDataRequest callback re-sends config if needed
5. Upload fails or board not recognized
- Install the latest Arduino UNO R4 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 mastering the Bluetooth Plotter example, try:
- Bluetooth Table - For structured data display
- Bluetooth Monitor - For text-based data display
- Bluetooth Temperature - For gauge-style temperature display
- Multiple Bluetooth Apps - Combining plotter with other apps
Support
For additional help:
- Check the API Reference documentation
- Visit DIYables tutorials
- Arduino community forums