Arduino Nano ESP32 - DIYables Bluetooth App Multiple Apps
Overview
This example demonstrates running 9 Bluetooth app widgets simultaneously on a single Arduino Nano ESP32 using BLE. Using BLE (Bluetooth Low Energy), the sketch combines Monitor, Chat, Slider, Joystick, Temperature, Plotter, Table, Analog Gauge, and Rotator into one sketch. All widgets share a single BLE connection and can interact with each other. Suitable for comprehensive dashboards, complex IoT projects, and learning multiple widget types at once.
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
- 9 Widgets in One: Monitor, Chat, Slider, Joystick, Temperature, Plotter, Table, Analog Gauge, Rotator
- Cross-Widget Interaction: Slider updates gauge and table; joystick updates table, etc.
- Single BLE Connection: All widgets share one connection efficiently
- Real-Time Updates: Each widget updates at its own configured interval
- Comprehensive Dashboard: View all data from a single device
- Android & iOS Support: BLE is compatible with both platforms
- No Pairing Required: BLE connects without manual pairing
Included Apps
| App | Description | Update Interval |
|---|---|---|
| Monitor | Text-based status display | 5 seconds |
| Chat | Two-way text messaging | On demand |
| Slider | Value control (0-255) | On change |
| Joystick | 2D position control | On change |
| Temperature | Temperature gauge (-10 to 50°C) | 2 seconds |
| Plotter | Real-time data graph | 100ms |
| Table | Structured data (10 rows) | 5 seconds |
| Analog Gauge | Dial-style gauge (0-100%) | 3 seconds |
| Rotator | Angle control (continuous) | On change |
Hardware Preparation
Or you can buy the following kits:
| 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_MultipleApps, or paste the code into the editor.
/*
* DIYables Bluetooth Library - ESP32 BLE Multiple Apps Example
* Works with DIYables Bluetooth STEM app on Android and iOS
*
* This example demonstrates how to use multiple Bluetooth apps simultaneously:
* - Monitor, Chat, Slider, Joystick, Temperature, Plotter,
* Table, Analog Gauge, Rotator
*
* Tutorial: https://diyables.io/bluetooth-app
* Author: DIYables
*/
#include <DIYables_BluetoothServer.h>
#include <DIYables_BluetoothMonitor.h>
#include <DIYables_BluetoothChat.h>
#include <DIYables_BluetoothSlider.h>
#include <DIYables_BluetoothJoystick.h>
#include <DIYables_BluetoothTemperature.h>
#include <DIYables_BluetoothPlotter.h>
#include <DIYables_BluetoothTable.h>
#include <DIYables_BluetoothAnalogGauge.h>
#include <DIYables_BluetoothRotator.h>
#include <platforms/DIYables_Esp32BLE.h>
// BLE Configuration
const char* DEVICE_NAME = "ESP32BLE Multi-App";
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 app instances
DIYables_BluetoothMonitor bluetoothMonitor;
DIYables_BluetoothChat bluetoothChat;
DIYables_BluetoothSlider bluetoothSlider(0, 255, 1);
DIYables_BluetoothJoystick bluetoothJoystick(false, 5);
DIYables_BluetoothTemperature bluetoothTemperature(-10.0, 50.0, "°C");
DIYables_BluetoothPlotter bluetoothPlotter;
DIYables_BluetoothTable bluetoothTable;
DIYables_BluetoothAnalogGauge bluetoothGauge(0.0, 100.0, "%");
DIYables_BluetoothRotator bluetoothRotator(ROTATOR_MODE_CONTINUOUS);
// State variables
int currentSlider1 = 128;
int currentSlider2 = 64;
int currentJoystickX = 0;
int currentJoystickY = 0;
float currentTemperature = 25.0;
float currentGaugeValue = 50.0;
float currentRotatorAngle = 0.0;
int messageCount = 0;
// Timing variables
unsigned long lastMonitorUpdate = 0;
unsigned long lastTempUpdate = 0;
unsigned long lastPlotUpdate = 0;
unsigned long lastTableUpdate = 0;
unsigned long lastGaugeUpdate = 0;
float plotPhase = 0;
void setup() {
Serial.begin(115200);
delay(1000);
Serial.println("DIYables Bluetooth - ESP32 BLE Multiple Apps Example");
pinMode(2, OUTPUT);
digitalWrite(2, LOW);
bluetoothServer.begin();
bluetoothServer.addApp(&bluetoothMonitor);
bluetoothServer.addApp(&bluetoothChat);
bluetoothServer.addApp(&bluetoothSlider);
bluetoothServer.addApp(&bluetoothJoystick);
bluetoothServer.addApp(&bluetoothTemperature);
bluetoothServer.addApp(&bluetoothPlotter);
bluetoothServer.addApp(&bluetoothTable);
bluetoothServer.addApp(&bluetoothGauge);
bluetoothServer.addApp(&bluetoothRotator);
Serial.print("Registered apps: ");
Serial.println(bluetoothServer.getAppCount());
bluetoothPlotter.setPlotTitle("Sensor Data");
bluetoothPlotter.setAxisLabels("Time", "Value");
bluetoothPlotter.setYAxisRange(-1.5, 1.5);
bluetoothPlotter.setMaxSamples(100);
bluetoothPlotter.setLegendLabels("Sine", "Cosine", "Random");
bluetoothTable.addRow("Status");
bluetoothTable.addRow("Uptime");
bluetoothTable.addRow("Slider 1");
bluetoothTable.addRow("Slider 2");
bluetoothTable.addRow("Joystick X");
bluetoothTable.addRow("Joystick Y");
bluetoothTable.addRow("Temperature");
bluetoothTable.addRow("Gauge Value");
bluetoothTable.addRow("Rotator Angle");
bluetoothTable.addRow("Messages");
setupCallbacks();
Serial.println("Waiting for Bluetooth connection...");
}
void setupCallbacks() {
bluetoothServer.setOnConnected([]() {
Serial.println("Bluetooth connected!");
digitalWrite(2, HIGH);
bluetoothMonitor.send("=== ESP32 BLE Multi-App Connected ===");
bluetoothMonitor.send("All apps are ready!");
bluetoothChat.send("Hello! ESP32 BLE Multi-App is connected.");
});
bluetoothServer.setOnDisconnected([]() {
Serial.println("Bluetooth disconnected!");
digitalWrite(2, LOW);
});
bluetoothMonitor.onMonitorMessage([](const String& message) {
Serial.println("Monitor cmd: " + message);
if (message == "HELP") {
bluetoothMonitor.send("Commands: STATUS, HELP, LED_ON, LED_OFF, HEAP");
} else if (message == "STATUS") {
bluetoothMonitor.send("Slider1=" + String(currentSlider1) + " Slider2=" + String(currentSlider2));
bluetoothMonitor.send("Joystick X=" + String(currentJoystickX) + " Y=" + String(currentJoystickY));
bluetoothMonitor.send("Temp=" + String(currentTemperature, 1) + "°C");
bluetoothMonitor.send("Gauge=" + String(currentGaugeValue, 1) + "%");
bluetoothMonitor.send("Rotator=" + String(currentRotatorAngle, 0) + "°");
} else if (message == "LED_ON") {
digitalWrite(2, HIGH);
bluetoothMonitor.send("LED turned ON");
} else if (message == "LED_OFF") {
digitalWrite(2, LOW);
bluetoothMonitor.send("LED turned OFF");
} else if (message == "HEAP") {
bluetoothMonitor.send("Free heap: " + String(ESP.getFreeHeap()) + " bytes");
} else {
bluetoothMonitor.send("Unknown: " + message + " (type HELP)");
}
});
bluetoothChat.onChatMessage([](const String& message) {
Serial.println("Chat: " + message);
bluetoothChat.send("Echo: " + message);
if (message.equalsIgnoreCase("ping")) {
bluetoothChat.send("pong!");
} else if (message.equalsIgnoreCase("status")) {
bluetoothChat.send("Uptime: " + String(millis() / 1000) + "s, Apps: " + String(bluetoothServer.getAppCount()));
}
});
bluetoothSlider.onSliderValue([](int slider1, int slider2) {
currentSlider1 = slider1;
currentSlider2 = slider2;
Serial.print("Slider 1: "); Serial.print(slider1);
Serial.print(", Slider 2: "); Serial.println(slider2);
currentGaugeValue = map(slider1, 0, 255, 0, 100);
bluetoothGauge.send(currentGaugeValue);
bluetoothTable.sendValueUpdate("Slider 1", String(slider1));
bluetoothTable.sendValueUpdate("Slider 2", String(slider2));
bluetoothTable.sendValueUpdate("Gauge Value", String(currentGaugeValue, 1) + "%");
});
bluetoothSlider.onGetConfig([]() {
bluetoothSlider.send(currentSlider1, currentSlider2);
});
bluetoothJoystick.onJoystickValue([](int x, int y) {
currentJoystickX = x;
currentJoystickY = y;
Serial.print("Joystick X: "); Serial.print(x);
Serial.print(", Y: "); Serial.println(y);
bluetoothTable.sendValueUpdate("Joystick X", String(x));
bluetoothTable.sendValueUpdate("Joystick Y", String(y));
});
bluetoothJoystick.onGetConfig([]() {
bluetoothJoystick.send(currentJoystickX, currentJoystickY);
});
bluetoothTemperature.onTemperatureRequest([]() {
bluetoothTemperature.send(currentTemperature);
});
bluetoothPlotter.onDataRequest([]() {
Serial.println("Plotter data requested");
});
bluetoothTable.onDataRequest([]() {
Serial.println("Table data requested");
bluetoothTable.sendTableStructure();
updateAllTableValues();
});
bluetoothGauge.onValueRequest([]() {
bluetoothGauge.send(currentGaugeValue);
});
bluetoothRotator.onRotatorAngle([](float angle) {
currentRotatorAngle = angle;
Serial.print("Rotator: "); Serial.print(angle); Serial.println("°");
bluetoothTable.sendValueUpdate("Rotator Angle", String(angle, 0) + "°");
});
}
void updateAllTableValues() {
bluetoothTable.sendValueUpdate("Status", "Running");
unsigned long uptime = millis() / 1000;
String uptimeStr;
if (uptime >= 60) {
uptimeStr = String(uptime / 60) + "m " + String(uptime % 60) + "s";
} else {
uptimeStr = String(uptime) + "s";
}
bluetoothTable.sendValueUpdate("Uptime", uptimeStr);
bluetoothTable.sendValueUpdate("Slider 1", String(currentSlider1));
bluetoothTable.sendValueUpdate("Slider 2", String(currentSlider2));
bluetoothTable.sendValueUpdate("Joystick X", String(currentJoystickX));
bluetoothTable.sendValueUpdate("Joystick Y", String(currentJoystickY));
bluetoothTable.sendValueUpdate("Temperature", String(currentTemperature, 1) + " °C");
bluetoothTable.sendValueUpdate("Gauge Value", String(currentGaugeValue, 1) + "%");
bluetoothTable.sendValueUpdate("Rotator Angle", String(currentRotatorAngle, 0) + "°");
bluetoothTable.sendValueUpdate("Messages", String(messageCount));
}
void loop() {
bluetoothServer.loop();
if (!bluetooth.isConnected()) {
delay(10);
return;
}
if (millis() - lastMonitorUpdate >= 5000) {
lastMonitorUpdate = millis();
messageCount++;
bluetoothMonitor.send("[INFO] Heartbeat #" + String(messageCount) + " - Uptime: " + String(millis() / 1000) + "s");
}
if (millis() - lastTempUpdate >= 2000) {
lastTempUpdate = millis();
static float tempOffset = 0;
tempOffset += random(-10, 11) / 10.0;
if (tempOffset > 5.0) tempOffset = 5.0;
if (tempOffset < -5.0) tempOffset = -5.0;
currentTemperature = 25.0 + tempOffset;
bluetoothTemperature.send(currentTemperature);
bluetoothTable.sendValueUpdate("Temperature", String(currentTemperature, 1) + " °C");
}
if (millis() - lastPlotUpdate >= 100) {
lastPlotUpdate = millis();
float sine = sin(plotPhase);
float cosine = cos(plotPhase);
float noise = random(-50, 51) / 100.0;
bluetoothPlotter.send(sine, cosine, noise);
plotPhase += 0.1;
if (plotPhase > 2 * PI) plotPhase = 0;
}
if (millis() - lastTableUpdate >= 5000) {
lastTableUpdate = millis();
unsigned long uptime = millis() / 1000;
String uptimeStr;
if (uptime >= 60) {
uptimeStr = String(uptime / 60) + "m " + String(uptime % 60) + "s";
} else {
uptimeStr = String(uptime) + "s";
}
bluetoothTable.sendValueUpdate("Uptime", uptimeStr);
bluetoothTable.sendValueUpdate("Messages", String(messageCount));
}
if (millis() - lastGaugeUpdate >= 3000) {
lastGaugeUpdate = millis();
float sensorValue = 50.0 + 30.0 * sin(millis() / 10000.0);
currentGaugeValue = sensorValue;
bluetoothGauge.send(currentGaugeValue);
bluetoothTable.sendValueUpdate("Gauge Value", String(currentGaugeValue, 1) + "%");
}
delay(10);
}
- Click Upload to flash the sketch to the board.
- Open the Serial Monitor.
- The Serial Monitor output should look like:
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Nano ESP32' on 'COM15')
New Line
9600 baud
DIYables Bluetooth - Multiple Apps Example
Waiting for Bluetooth connection...
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 "DIYables Multi-App" in the scan results.
- After connecting, the home screen displays all available app widgets. The 9 widgets initialised in the Arduino sketch will respond and function — other widgets on the home screen will appear but will not work with this sketch.
Tap the settings icon on the home screen to show or hide apps. See the DIYables Bluetooth App User Manual for details.
- Open any of the following widgets to interact with the Arduino: Monitor, Chat, Slider, Joystick, Temperature, Plotter, Table, Analog Gauge, Rotator.
- Switch between widgets freely — all share the same BLE connection.
Now look back at the Serial Monitor on Arduino IDE. You will see:
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Nano ESP32' on 'COM15')
New Line
9600 baud
Bluetooth connected!
Monitor: System running, uptime: 5s
Chat message: Hello
Slider value: 128
Joystick: X=0.50, Y=-0.30
Temperature: 22.50 °C
How It Works
App Initialisation
Each widget is created with its own configuration and callbacks:
// All apps share the same Bluetooth server
DIYables_BluetoothServer bluetoothServer(bluetooth);
// Create individual apps
DIYables_BluetoothMonitor bluetoothMonitor(bluetoothServer);
DIYables_BluetoothChat bluetoothChat(bluetoothServer);
DIYables_BluetoothSlider bluetoothSlider(bluetoothServer, 0, 255, 1);
DIYables_BluetoothJoystick bluetoothJoystick(bluetoothServer, false, 5);
DIYables_BluetoothTemperature bluetoothTemp(bluetoothServer, -10.0, 50.0, "°C");
DIYables_BluetoothPlotter bluetoothPlotter(bluetoothServer);
DIYables_BluetoothTable bluetoothTable(bluetoothServer);
DIYables_BluetoothAnalogGauge bluetoothGauge(bluetoothServer, 0.0, 100.0, "%");
DIYables_BluetoothRotator bluetoothRotator(bluetoothServer, ROTATOR_MODE_CONTINUOUS);
Cross-App Interaction
Apps can interact with each other. When one widget receives input, it can update other widgets:
// Slider updates gauge and table
bluetoothSlider.onSliderValue([](int value) {
float percent = value * 100.0 / 255.0;
bluetoothGauge.send(percent);
bluetoothTable.sendValueUpdate("Slider 1", String(value));
});
// Joystick updates table
bluetoothJoystick.onJoystickValue([](float x, float y) {
bluetoothTable.sendValueUpdate("Joystick X", String(x, 2));
bluetoothTable.sendValueUpdate("Joystick Y", String(y, 2));
});
// Rotator updates table
bluetoothRotator.onRotatorAngle([](float angle) {
bluetoothTable.sendValueUpdate("Rotator Angle", String(angle, 1) + "°");
});
Update Timing
Each app has its own update interval to balance responsiveness with BLE bandwidth:
void loop() {
bluetoothServer.loop();
unsigned long now = millis();
// Plotter: fastest updates (100ms)
if (now - lastPlotterTime >= 100) { ... }
// Temperature: every 2 seconds
if (now - lastTempTime >= 2000) { ... }
// Gauge: every 3 seconds
if (now - lastGaugeTime >= 3000) { ... }
// Monitor, Table: every 5 seconds
if (now - lastMonitorTime >= 5000) { ... }
if (now - lastTableTime >= 5000) { ... }
}
Table Structure
The example creates a table with 10 rows showing data from all apps:
| Row | Label | Description |
|---|---|---|
| 0 | Status | Connection/running status |
| 1 | Uptime | Time since boot |
| 2 | Slider 1 | Current slider value |
| 3 | Slider 2 | Second slider value |
| 4 | Joystick X | Joystick X position |
| 5 | Joystick Y | Joystick Y position |
| 6 | Temperature | Current temperature |
| 7 | Gauge Value | Current gauge percentage |
| 8 | Rotator Angle | Current rotation angle |
| 9 | Messages | Chat message count |
Creative Customization - Adapt the Code to Your Project
Add or Remove Widgets
Include only the widgets required for your project:
// Minimal setup: just Monitor and Slider
DIYables_BluetoothMonitor bluetoothMonitor(bluetoothServer);
DIYables_BluetoothSlider bluetoothSlider(bluetoothServer, 0, 100, 1);
// That's it! The app will only show these two
Custom Cross-App Logic
// Example: Temperature alarm via Monitor
void checkTemperatureAlarm(float temp) {
if (temp > 40.0) {
bluetoothMonitor.send("⚠️ HIGH TEMP ALERT: " + String(temp, 1) + "°C");
bluetoothChat.send("Temperature alarm triggered!");
}
}
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. Some widgets not showing in the menu
- All initialised widgets will appear automatically
- Verify each widget object is properly created
- The app discovers available widgets from the Arduino
3. Updates seem slow
- Each widget has different update intervals by design
- BLE bandwidth is limited; too many rapid updates can cause congestion
- Reduce update frequency for widgets that do not require real-time data
4. Cross-widget updates not working
- Verify the callback functions are properly registered
- Check that table row names match exactly (case-sensitive)
- Confirm the target widget object is accessible within the callback scope
5. Memory issues or crashes
- Running 9 widgets uses significant memory
- Remove unused widgets to free resources
- Reduce table row count if needed
6. 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
- Comprehensive IoT dashboard
- Robot control panel (joystick + monitor + sliders)
- Weather station (temperature + gauge + plotter + table)
- Home automation hub (sliders + pins + monitor + chat)
- STEM learning platform (all apps for experimentation)
Next Steps
After completing the Multiple Apps example, explore each individual tutorial for deeper understanding:
- Bluetooth Chat — Messaging details
- Bluetooth Slider — Value control details
- Bluetooth Plotter — Data visualisation details
- Bluetooth RTC — Time synchronisation using the built-in hardware RTC
Support
For additional help:
- Check the API Reference documentation
- Visit DIYables tutorials
- Arduino community forums