Connecting arduino mega via bluetooth to multiple devices

Hi, I am creating a class management tool for primary schools for my Year 12 Major Project.
I am aiming to wirelessly connect multiple screens such as OLED Display modules to a teacher’s device that has buttons on it to warn children about their behaviour and have timers etc on it.
How do I achieve this via Bluetooth connection and using Arduino Mega?

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Hi Xanthi! Welcome. :slight_smile:

That’s a sweet project.

What about the HC-05. I have limited experience with it but I understand it’s a tested staple. I was helping a friend where an HC-05 was involved and found it easy to work with in that context.

Are the OLED Display modules something you already own? Are they Bluetooth ?

You might like to have two Arduino’s, one as your MASTER control unit and the other as a SLAVE receiver unit.
The slave can then receive instructions from the master and put the correct text up on screen.

Core has a guide :slight_smile:

Concerning the multiple screens, do they all receive the sames message at the same time, or are you wanting different messages on each at different times ?

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I would like the screens to receive different messages - for example, one button press sends a signal to the connected Arduino to light up green.

Ah ok!

Do you already own these oled displays?
If so what are there model numbers?
Are the connected to a device already?

If you dont already own these displays, how big would you like them to be?

I do not own OLED displays, however I would like the 1.5 inch ones.

Would this display work for you?

I used a Jaycar USB Host Shield with a USB dongle connected to an Arduino Mega.
The dongle communicated with a Playstation Controller to control a robot cart.
Pretty easy to get going and everything just plugged in.

In your case it would be a little different trying to communicate with multiple devices.
Bluetooth likes to pair so it would be connecting and disconnecting.
Maybe setting up the Mega as a WiFi hotspot would be a better option.

Anyway sounds interesting.


This would probably require Bluetooth BLE in broadcast mode. The alternative is to connect and disconnect from each receiving device, and that becomes quite complex and slow.

The broadcast message would contain a recipient ID. The devices you broadcast to would require code that responds to a particular ID to display the message.

So your research could start by searching on ‘BlueTooth Broadcast Mode’ or ‘BLE Broadcast’. The feature you want is called ‘Advertising’, although that’s not a formal mode. The packet size is small, but as the code to interpret the packet (eg, a standard text string) is in the receiving device then the available space should be adequate. The problem might be that all devices in the room would go ding even though only one displays a message!