How to send sensor data from multiple peripheral devices simultaneously to one central device

[masterLee]

Hi,

I have created a system with nRF52840 (peripheral) that collects data from an accelerometer and gyroscope sensors and sends those data through ble_uart to a smartphone  device (central) for visual inspection (graph).

The system works fine but now I want to move a step further and send sensor data from multiple peripherals simultaneously to the same smartphone device so that I can display data from all devices in the same graph

The possible configurations I can think of, are the following.

• 1st possible Configuration
  • Collect the data from multiple peripheral devices simultaneously and
  • display those data on  smartphone app
• 2nd Possible Configuration
  • Collect the data from multiple peripheral devices simultaneously and
  • send them to an nRF52840 central device that assemblies all that data into packets and then
  •  send those packets to a smartphone device and display them  

                                   

The problem is that, I don't know if and how multiple peripherals can be connected all together at the same time

to a central (either configuration 1 or 2) in order to receive data from all devices simultaneously.

Do you know if there is some example or tutorial that does that, so I can use it as basis ?

Thank you for your time

Best regards

[Sigurd]

Hi,

Both configurations are possible. The SoftDevice can support 20 concurrent Bluetooth Low Energy connections. We have a ble_app_multilink_central example in the nRF5-SDK.

You can also find a multi-link version of ble_app_uart_c in this github repo: https://github.com/NordicPlayground/nrf52-ble-app-uart-c-multilink

[masterLee]

I will check them out. Thank you so much for your support! I will leave this post open for a few days in case I find some difficulty.

Best Regards

[Tai]

Hi masterLee Hope you successfully finished this project without any major issues. I'm also looking for a potential solution to send data from multiple peripheral devices to a central device. Hope to receive any suggestions from you. Thanks!

[masterLee]

Hi Tai, yes the project works as expected. No issues at all. I recommend you to check the following link and start playing with it. You will need at least 2 devices for start. One central with the firmware given in the following link and  one peripheral with NUS service.

github.com/.../nrf52-ble-app-uart-c-multilink.

The central device "understands" peripheral devices that run the NUS service so it will filter out all other BLE devices i.e. headphones etc. Now, if you want to communicate with certain NUS peripherals you will need to find the device IDs of those peripherals and create a list of them in the central firmware. 

[Tai]

Thanks for your suggestion, masterLee ! Following the reply from Sigurd in this thread, I also downloaded and successfully complied ble_app_uart_multilink central device. Here is my plan:

1. Having a board (e.g., nRF52840) acts as both central & peripheral mode so that it can receive data from 2 peripheral devices (e.g., nRF52832) and it can also send data to an IOS application.
2. For 2 peripheral devices, I have one with NUS server, and the other one with custom BLE service. In this scenario do you think I should update the latter using NUS server as well? Or I can keep it with the custom BLE service, and I still can let it communicate with the central device?

Any thoughts? I would much appreciate it. Thanks.

[masterLee]

I haven't implemented the plan you mention so I will not be helpful. In order for the example to work all devices must use Nordic Uart Service (at least as far as I know). So you will need to test all your assumptions to be sure if they work.

[Tai]

Thanks masterLee ! I actually separated my above plan into smaller chunks. The first one is to connect multiple peripherals to a central device which I believe it's similar to yours. I tagged you to my post and hope to receive any comments/suggestions on that. In case I can't find it, I added the link of my post here. Thanks!

Option for better throughput with BLE multi-link/multi-role - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com)

[masterLee]

Ok, Thanks for tagging me!  Yes the first part is basically the same as mine I believe.  I will read the post!