How to Change Scrolling Text on MAX7219 LED Matrix Display Via Bluetooth Using Arduino (Step-by-Step Guide)

Scrolling LED displays are one of the most attractive and useful electronics projects for beginners and makers. In my previous tutorial, we built an 8×32 MAX7219 LED Matrix Scrolling Display using Arduino that shows fixed text. Now let’s take this project one step further and make it smart and wireless.

In this tutorial, you will learn how to change the scrolling text on a MAX7219 LED matrix display using Bluetooth without re-uploading the Arduino code every time. By using a Bluetooth module and a mobile phone, you can instantly update any message you want—names, quotes, shop banners, notice boards, or greetings—directly from your phone.

This project is perfect for digital notice boards, shop displays, office desks, and DIY smart signage systems. Even if you are a beginner, don’t worry—everything is explained step by step, from understanding the concept to wiring, code logic, and final testing.

By the end of this tutorial, you will have a fully customizable scrolling LED display that looks professional and works wirelessly using Bluetooth communication.

Let’s get started and turn a simple scrolling display into a smart Bluetooth-controlled LED message board.

For this tutorial, no extra hardware is needed except one additional module. We will use the same MAX7219 LED matrix display and Arduino setup from the previous tutorial.

1. HC-05 Bluetooth Module
2. The HC-05 Bluetooth module allows us to send text wirelessly from a mobile phone to the Arduino, making it possible to change the scrolling message without uploading new code again and again.

The HC-05 Bluetooth module has a total of 6 pins, but for this project we will use only 4 pins.

1. +5V
2. GND
3. TX
4. RX

Now connect the Bluetooth module to the Arduino as follows:

1. RX pin of HC-05 → TX pin of Arduino
2. TX pin of HC-05 → RX pin of Arduino
3. GND → GND of Arduino
4. +5V → +5V of Arduino

🔹 Make sure the TX and RX pins are cross-connected, otherwise Bluetooth communication will not work properly.

After making these connections, your Bluetooth module will be ready to receive text data from a mobile phone and send it to the Arduino for scrolling on the MAX7219 LED matrix display.

Now we need to upload the code again to make the MAX7219 display accept text from the Bluetooth module.

1. Connect the Arduino Nano to your laptop
2. Plug the Type-B USB cable into the Arduino Nano and connect the other end to your laptop.
3. Bluetooth LED indication
4. Once powered, you will notice that the LED on the HC-05 Bluetooth module starts blinking fast, which indicates that the module is powered and waiting for connection.
5. Open Arduino IDE
6. Launch the Arduino IDE on your computer.
7. Open the example code

Navigate through the menu as follows:

1. File → Examples → MD_MAX72xx → MD_MAX72xx_Message_Serial
2. Modify the code settings
3. In the opened code:
4. Select the correct hardware type for your MAX7219 module.
5. Set Maximum Devices according to how many 8×8 MAX7219 LED matrices are connected in your display.
6. Adjust the scroll delay as per your preference (lower value = faster scrolling).
7. Change the serial baud rate
8. Scroll down to the void setup() section and find this line:
9. Serial.begin(57600);

Change it to:

1. Serial.begin(9600);

This is important because the HC-05 Bluetooth module communicates at 9600 baud rate by default.

7.Disconnect RX and TX before uploading

Before uploading the code, disconnect the RX and TX pins of the Bluetooth module from the Arduino.

This prevents upload errors and communication conflicts.

8.Upload the code

Go to Tools and make sure:

1. The correct Board (Arduino Nano)
2. The correct Processor
3. The correct COM Port
4. are selected.
5. Now click on Upload.

9.Reconnect Bluetooth pins

After the code is uploaded successfully, reconnect the RX and TX pins of the Bluetooth module.

10.Final check

Once everything is connected again, you will see that the text starts scrolling on the MAX7219 LED display, confirming that the code is running correctly.

Now we will use a mobile phone to send text wirelessly to the MAX7219 scrolling display.

1. Install the required app
2. Open the Play Store on your phone and install an app called “Serial Bluetooth Terminal”.
3. Open app settings
4. After installation, open the app.
5. Tap on the three lines (☰) at the top-left corner, then go to Settings.
6. Change receive settings
7. In Settings:
8. Tap on Receive
9. In New Line, select LF
10. This setting ensures that the text you send is properly recognized by the Arduino.
11. Turn on Bluetooth and connect the module
12. Turn ON Bluetooth on your phone.
13. Again tap on the three lines (☰) → go to Devices.
14. From the list, select the Bluetooth name of your HC-05 module and connect to it.
15. Check Bluetooth connection status
16. At the bottom of the app, it will show Connected or Disconnected
17. At the top-right corner, a Bluetooth symbol will appear once connected
18. On the hardware side, the HC-05 LED blinking pattern will change from fast blinking to slow blinking, confirming a successful connection
19. Send text to the display
20. Now, at the bottom text input area of the app:
21. Type any message you want
22. Press Send
23. The text will instantly start scrolling on the MAX7219 LED matrix display.

You can send:

1. Text messages
2. Numbers
3. Different font styles

This makes the display fully customizable in real time, without uploading code again.

This app also allows us to save preset messages, so you don’t have to type the same text again and again.

1. Create a preset message
2. In the Serial Bluetooth Terminal app, long press on the M1 button.
3. A new window interface will pop up.
4. Write and save the text
5. In this window:
6. Type any text you want to scroll on the display
7. Save the message
8. Print the preset text
9. Now, just tap on M1 once.
10. You will instantly see that the saved text starts scrolling on the MAX7219 LED matrix display.

Using presets is very useful for fixed messages, shop names, welcome text, or daily notices, making this project even more practical and professional.

Keep in mind that once the power is lost, the scrolling display will start showing the default text that is already written inside the Arduino code.

This happens because the Bluetooth text is not stored permanently in memory. After restarting, the Arduino runs the program again and prints the predefined message from the code.

However, once the display is powered ON again, you can easily control and change the scrolling text using Bluetooth from your mobile phone, just like we did in the previous steps.

This way, the display remains fully functional, wireless, and controllable via Bluetooth, making it perfect for smart notice boards, shop displays, and DIY LED message systems.

In this project, we successfully upgraded a simple MAX7219 LED matrix scrolling display into a smart, Bluetooth-controlled message board. By adding just an HC-05 Bluetooth module, we made it possible to change scrolling text wirelessly from a mobile phone, without uploading the Arduino code again and again.

This step-by-step tutorial showed how to connect the Bluetooth module, modify the Arduino example code, and use a mobile app to send text in real time. The preset feature makes it even more practical by allowing quick access to frequently used messages. Although the display resets to the default text after power loss, it can instantly be controlled again through Bluetooth, keeping the system simple and reliable.

This project is ideal for shop name boards, notice displays, office desks, study tables, and DIY smart signage. It is low-cost, beginner-friendly, and highly customizable, and can be further upgraded with features like EEPROM memory, Wi-Fi control, or a dedicated mobile app.

I hope this tutorial helps you build your own Bluetooth-controlled scrolling LED display. If you found this project useful, try customizing it further and share your version with others. Happy making!