Arduino UNO R4 - DIYables Bluetooth App Table
Overview
The Bluetooth Table example provides structured data display through the DIYables Bluetooth STEM app. Designed for Arduino UNO R4 WiFi using BLE (Bluetooth Low Energy) to display sensor readings, system status, and any data in a clean table format on your smartphone. Supports named rows with real-time value updates. Perfect for dashboards, system monitoring, and multi-sensor displays.
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
- Named Rows: Define rows with labels (e.g., "Temperature", "Humidity")
- Real-Time Updates: Push individual value updates efficiently
- Structure Sync: Auto-send table structure on connection
- Flexible Data: Display any string or numeric data
- Up to 20 Rows: Support for multiple data fields
- 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) |
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 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_Table example, or copy the above code and paste it to the editor of Arduino IDE
/*
* DIYables Bluetooth Library - Bluetooth Table Example
* Works with DIYables Bluetooth STEM app on Android and iOS
*
* This example demonstrates the Bluetooth Table feature:
* - Display structured data in a two-column table
* - Real-time value updates for each row
* - Perfect for sensor dashboards and status displays
*
* 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 table
*
* Tutorial: https://diyables.io/bluetooth-app
* Author: DIYables
*/
#include <DIYables_BluetoothServer.h>
#include <DIYables_BluetoothTable.h>
#include <platforms/DIYables_ArduinoBLE.h>
// BLE Configuration
const char* DEVICE_NAME = "Arduino_Table";
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 Table app instance
DIYables_BluetoothTable bluetoothTable;
// Variables for demo data
unsigned long lastUpdate = 0;
const unsigned long UPDATE_INTERVAL = 1000; // Update every second
int counter = 0;
void setup() {
Serial.begin(9600);
while (!Serial);
Serial.println("DIYables Bluetooth - Table Example");
// Initialize Bluetooth server with platform-specific implementation
bluetoothServer.begin();
// Add table app to server
bluetoothServer.addApp(&bluetoothTable);
// Define table structure (add rows with attribute names)
bluetoothTable.addRow("Temperature");
bluetoothTable.addRow("Humidity");
bluetoothTable.addRow("Pressure");
bluetoothTable.addRow("Counter");
bluetoothTable.addRow("Uptime");
bluetoothTable.addRow("Free Memory");
bluetoothTable.addRow("Status");
Serial.print("Table rows defined: ");
Serial.println(bluetoothTable.getRowCount());
// Set up connection event callbacks
bluetoothServer.setOnConnected([]() {
Serial.println("Bluetooth connected!");
// Send table structure
bluetoothTable.sendTableStructure();
// Send initial values
updateTableValues();
});
bluetoothServer.setOnDisconnected([]() {
Serial.println("Bluetooth disconnected!");
});
// Optional: Handle requests for table data
bluetoothTable.onDataRequest([]() {
Serial.println("App requested table data");
bluetoothTable.sendTableStructure();
updateTableValues();
});
Serial.println("Waiting for Bluetooth connection...");
}
void updateTableValues() {
// TODO: Replace with actual sensor readings
// Simulated temperature (20-30°C)
float temperature = 20.0 + random(0, 100) / 10.0;
bluetoothTable.sendValueUpdate("Temperature", String(temperature, 1) + " °C");
// Simulated humidity (40-60%)
int humidity = 40 + random(0, 21);
bluetoothTable.sendValueUpdate("Humidity", String(humidity) + " %");
// Simulated pressure (1000-1020 hPa)
int pressure = 1000 + random(0, 21);
bluetoothTable.sendValueUpdate("Pressure", String(pressure) + " hPa");
// Counter value
bluetoothTable.sendValueUpdate("Counter", String(counter));
counter++;
// Uptime (in seconds)
unsigned long uptime = millis() / 1000;
String uptimeStr = String(uptime / 3600) + "h " +
String((uptime % 3600) / 60) + "m " +
String(uptime % 60) + "s";
bluetoothTable.sendValueUpdate("Uptime", uptimeStr);
// Free memory (simulated)
int freeMemory = 2048 - random(0, 512);
bluetoothTable.sendValueUpdate("Free Memory", String(freeMemory) + " bytes");
// Status
bluetoothTable.sendValueUpdate("Status", counter % 2 == 0 ? "Running" : "Active");
// Alternative: Update by index instead of attribute name
// bluetoothTable.sendValueUpdate(0, String(temperature, 1) + " °C");
// bluetoothTable.sendValueUpdate(1, String(humidity) + " %");
Serial.println("Table values updated");
}
void loop() {
// Handle Bluetooth server communications
bluetoothServer.loop();
// Update table values periodically (only when connected)
if (bluetooth.isConnected() && millis() - lastUpdate >= UPDATE_INTERVAL) {
lastUpdate = millis();
updateTableValues();
}
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 - Table 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_Table" in the scan results to connect.
- Once connected, the app automatically goes back to the home screen. Select the Table 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 table with rows showing Temperature, Humidity, Pressure, Counter, Uptime, Free Memory, and Status — all updating in real time
Now look back at the Serial Monitor on Arduino IDE. You will see:
COM6
Bluetooth connected!
Sending table updates...
Temperature: 25.30 °C
Humidity: 55.70 %
Autoscroll
Clear output
9600 baud
Newline
Creative Customization - Adapt the Code to Your Project
Define Table Structure
// Add rows during setup
bluetoothTable.addRow("Temperature", "-- °C");
bluetoothTable.addRow("Humidity", "-- %");
bluetoothTable.addRow("Pressure", "-- hPa");
bluetoothTable.addRow("Status", "Initializing...");
Update Values
// Update by row name
bluetoothTable.sendValueUpdate("Temperature", "25.5 °C");
bluetoothTable.sendValueUpdate("Status", "Running");
// Update by row index (0-based)
bluetoothTable.sendValueUpdate(0, "25.5 °C");
bluetoothTable.sendValueUpdate(3, "Running");
Send Table Structure
// Re-send the full table structure to the app
bluetoothTable.sendTableStructure();
// Handle data request from app
bluetoothTable.onDataRequest([]() {
bluetoothTable.sendTableStructure();
});
Programming Examples
Weather Station Dashboard
DIYables_BluetoothTable bluetoothTable(bluetoothServer);
void setup() {
bluetoothTable.addRow("Temperature", "-- °C");
bluetoothTable.addRow("Humidity", "-- %");
bluetoothTable.addRow("Pressure", "-- hPa");
bluetoothTable.addRow("Wind Speed", "-- m/s");
bluetoothTable.addRow("Rain", "None");
bluetoothTable.onDataRequest([]() {
bluetoothTable.sendTableStructure();
});
}
void loop() {
bluetoothServer.loop();
static unsigned long lastTime = 0;
if (millis() - lastTime >= 2000) {
lastTime = millis();
bluetoothTable.sendValueUpdate("Temperature", String(readTemp(), 1) + " °C");
bluetoothTable.sendValueUpdate("Humidity", String(readHumidity(), 1) + " %");
bluetoothTable.sendValueUpdate("Pressure", String(readPressure(), 0) + " hPa");
}
}
System Status Monitor
void setup() {
bluetoothTable.addRow("Uptime", "0s");
bluetoothTable.addRow("Free RAM", "-- bytes");
bluetoothTable.addRow("WiFi RSSI", "-- dBm");
bluetoothTable.addRow("IP Address", "N/A");
bluetoothTable.addRow("Status", "Starting...");
}
void loop() {
bluetoothServer.loop();
static unsigned long lastTime = 0;
if (millis() - lastTime >= 1000) {
lastTime = millis();
unsigned long uptime = millis() / 1000;
String uptimeStr = String(uptime / 3600) + "h " + String((uptime % 3600) / 60) + "m " + String(uptime % 60) + "s";
bluetoothTable.sendValueUpdate("Uptime", uptimeStr);
bluetoothTable.sendValueUpdate("Status", "Running");
}
}
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. Table is empty or rows not showing
- Ensure addRow() is called in setup() before connecting
- Implement the onDataRequest callback to re-send structure
- Verify sendTableStructure() is called
3. Values not updating
- Check that sendValueUpdate() is being called in the loop
- Verify the row name matches exactly (case-sensitive)
- Ensure bluetoothServer.loop() is called in every loop iteration
4. Row names don't match
- Row names are case-sensitive — "Temperature" ≠ "temperature"
- Use row index (0-based) as an alternative to row names
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
- Weather station dashboard
- System resource monitor
- Multi-sensor data display
- Device configuration panel
- IoT device status board
Next Steps
After mastering the Bluetooth Table example, try:
- Bluetooth Plotter - For graphical data visualization
- Bluetooth Monitor - For text-based interaction
- Bluetooth Temperature - For gauge-style display
- Multiple Bluetooth Apps - Combining table with other apps
Support
For additional help:
- Check the API Reference documentation
- Visit DIYables tutorials
- Arduino community forums