BluetoothLE extension: Can i get multiple BLE devices connected simultaneously

MIT App Inventor Help
1

Hello,
I need get my app connected to four BLE specific peripherical devices simultaneously?

Is this possible with BluetoothLE extension. What should I do?

Thanks in advance,
Osmany

2

It's not possible to make four connections simultaneously but if you know the addresses of all four and their Service/Characteristic UUIDS, you would be able to connect very quickly as that would negate the need to scan for them.

What are the four devices (Make, Model) and the goal of your Project?

3

Thanks @ChrisWard for your answer,

There are four (ESP32+NFC pn5180 frontend) devices that will be reading rfid tags at different possitions constantly. I need these devices to notify the central (ble client, i.e., mobile app) as soon as its tag inventory changes.

Currently, i've implemented a solution using a MQTT, then esp32 publishing (WIFI) to the mqtt broker (mosqutto), and the mobile app subscribed, but my devices are battery powered, so I want to change to bluetooth LE technology.

Any suggestion,

Thanks again,
Osmany

4

Hi

You say different positions, can you clarify that please. Also, the environment the devices will be subject to.

5

@ChrisWard,

Devices are multi-tag readers, i.e., they can inventory multiple near rfid tags at once. (Microcontroller + Vecinity Coupling Device), (RFID jargon).

There are four of them, located in four different locations.

I need kind of dashboard running on mobile or tablet to visualize inventory results from all devices in live.

Now, as i said, i´m using a MQTT client app subcribed to four topics, devices are clients publishing on those topics, and Mosquitto is the MQTT Broker.

I want to develop my own dashboard (and this is how I got to the App Inventor). But, i want to move to BLE technolgy, removing the broker from the middle and communicating via ble technology directly.

Grateful for your attention,
Osmany

6

It's the location bit that is critical - I'm guessing from what you have said that the set-up is indoors. They would have to be very near the RIFD tags would they not? What else is in the environment - for example are we talking about a supermarket, an airport, a warehouse, a house?

The environment and location of the BLE devices is critical given the BLE signal.

7

Hi @ChrisWard,

BLE signal strength will not be a problem. In fact, maybe distance must be restricted using RSSI. Some details....
-The peripherical devices will be no more than one meter from each other, in the same room.
-The central device (android device) should be in the same room.
-RFID antennas are calibrated to 18cm wide field (13.56 MHz, no interference).
-MQTT Brokers over Wifi TCP/IP is an oversized technology for my solution.

I already have tested BLE communication sucesfuly, using nRF Connect app from Nordic Semiconductors . Now, i need my own dashboard (BLE central or client).

When I was reading BluetoothLE extension reference I had the question about whether it can have more than one simultaneous connection.

Should i have four instances of BluetoothLE? Does it make sense?

Best regards,
Osmany

8

Well, I have already remarked that you can't achieve simultaneous connection with BLE but you can achieve fast connections. I think the best approach in the App would be four instances of BLE.

You already have the BLE boards? Why not build a simple connection test?

Rapidly copy-paste UUIDs from my site:
ProfessorCad: Tips & Tricks Create/Validate BLE UUIDs

If it's going to work, I imagine this would be how (mini test)

BLE_MULTI_DEVICES.aia (197.2 KB)

blocks
blocks763×1285 89.7 KB