IOS and macOS devices can't connect to BLE MIDI device (nrf52832)

[piotrosiotr]

Hello. I'm trying to make a simple BLE MIDI switch device based on PCA10040 dev kit and nrf Connect SDK v2.0.0. So I've added one GATT service with one characteristic according to BLE MIDI specification. All tutorials at this point say that I'll be able to discover this device and connect to it. Indeed, I can do it from Windows laptop. But when I try to connect it to macbook pro or iphone, I can't see my device at devices list at all (I tried BT settings on both of them, also I tried Audio/MIDI studio on mac and GarageBand on iphone, which are standart ways to discover BLE MIDI Devices). But when I go further and download some BLE scanner apps on my devices, I can see my PCA10040 and connect it. Furthermore, when I connect PCA10040 with scanner app, I can see and connect it using Audio/MIDI studio and GarageBand. 

I also have some common BLE MIDI controllers from Roli, Akai, etc and when I try to connect them, I can see them in BT settings without any additional manipulations.

So the question is: how to make my device scannable not only for scanner apps, but for default means on mac/iphone? I thought that the difference is in advertising modes, but I'm not shure about it. I've seen this behavior before when I tried to connect to some beacons.

[Menon]

Hello,

Did you connect your board earlier with the same iPhone/Mac book you are trying? If so, this might be because of the attribute caching. iOS keeps a history of the previous connection. So it doesn't want to rediscover the device. Could you clear your cache once and give it a try? You can do this by:

Settings--> Bluetooth--> Forget every Bluetooth device in the "My device list"--> Restart the phone/device.

Cache will be cleared after this. Let me know if this helps or whether you are still struggling to connect.

Kind Regards,

Abhijith

[piotrosiotr]

Yes, I've tried to clear all cashed BT devices, but it didn't help to me. I still can't see my device in Settings-->Bluetooth until I connect it using BLE Scanner app. I think that the reason is in the way in which default BLE search goes, it obviously different from BLE Scanner app, but I don't have any idea, in which way.
Thank you for reply.

[Menon]

Hello,

Whether you able to see the device through nRF connect application? Could you  please provide the IOS version you are trying with.

Kind Regards,

Abhijith

[piotrosiotr]

Hello,
Yes, I can. nRF Connect Device Manager also can see it. I use latest iOS (v16.0.2) and macOS Big Sur (v11.6.5).
King Regards,

Piotr

[Menon]

Hello,

I was checking whether there is any known issue with the IOS versions. Didn't find much on this. Could you provide the sniffer traces, So to get an idea on what's happening over the Air.

You can follow this guide for capturing the traces.

Kind Regards,

Abhijith