Multiple BLE UART Peripherals -> Single Phone Application

[scott.williams.113]

Hi there,

I have my system totally working now. I am looking to sell 1000-10000 units next year, so this is fantastic. I first want to say thank you to Nordic for all the support.

Basically, I have a fairly standard setup:

Light -> Light Sensor -> Light Sensor Data (Analogue Value) Transmitted Over Bluetooth -> Phone Receives Data

Right now, I am using the BLE UART Example to base my data transfer on (i.e. sending the analogue data as a string), and it works perfectly. However there is one thing I haven't fullfilled yet:

Multiple Sensors -> 1 Phone

Obviously, the nRF Toolbox UART App doesn't support that, as you can only connect to one device at a time. However, I was wondering if it was possible to do this if I made my own custom app? (Using the nRF Toolbox Source code as a guide, and somehow making multiple connection instances and connecting to multiple devices). And if so, how many would probably be the maximum?

I have experience developing small apps for both iOS and Android, so I am confident I can. I just wanted to make sure, from the app side of things, this is even possible.

Otherwise a solution I thought could be constantly disconnecting/reconnecting to each device one at a time to grab data from them, and keep their data in some sort of buffer until the transfer is done. That seems like a viable solution if I can't do multiple simultaneously.

I know Nordic has Mesh as a solution for what I'm talking about, but I have such a simple system (literally just 1 byte of data transferred occasionally, nothing else). So it seemed way too overkill to worry about setting up a Mesh network for this (plus I posted asking for help with Mesh and no one could help me, so here I am).

Thanks for your time :)

[awneil]

scott.williams.113 said:

using the BLE UART Example to base my data transfer on (i.e. sending the analogue data as a string)

Not related to your question, but you do realise that the NUS is not limited to strings - it is perfectly usable for binary data?

How multiple connections are (or aren't) handled on the phone is entirely down to the phone - nothing really to do with Nordic.

The place to go would be the iOS developer resources & communities.

Googling "ios multiple ble connections" gives, for instance: https://spin.atomicobject.com/2016/01/20/multiple-ble-devices-in-ios/ (although that's >2 years old).

[scott.williams.113]

1. Oh yeah, I mean at the end of the day a string is just binary that has been encoded yeah. I'm just saying strings as a general term since characters are conveniently 1 byte each, that's all.

2. Yeah I'm aware this is also an issue regarding the phone itself. But the fact is that Nordic UART Service is a protocal developed by Nordic, and I will be using the Toolbox source code as guide on how to implement this in an app. So the questions is definitely for Nordic whether the NUS method/protocal can be used for multiple devices on 1 phone. I believe so anyway.

[MartinBL]

Hi,

In general the NUS service is like any other service and it shouldn't be a problem to implement multiple instances of it on your phone. I'm no iOS programmer and the guy wrote nRF Toolbox for iOS is on holiday at the moment, so I can't comment on how re-usable the git hub code is though.

What might be stopping you is indeed, as awneil says, limitations on your phone. It is not a given that every chip set and implementation of the BLE stack support more than one link. 

[scott.williams.113]

Thanks for your information Martin. Really appreciate it. I'll have a go and just hope for the best, I guess!