Connected to two peripherals from one central

[StephaneJ]

Hi,

I'm using two nRF52832 (SDK14.2, SD132v5) to send data via Notify to one central. This central can be either a laptop or a smartphone.

The two nRF52832 has the same GATT Server configured but only the name of the peripheral change.

On my laptop there is no problem I can have both connected and received data from both.

But on Android (I don't have iOS to test), once I want to connect to the second board, the first one also receive a BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST as if it was a first connection request. But since it is already connected, it crash. I'm having this issue even with the nRF Connect app.

I can't reproduce it on my laptop (macOS). When I initiate a connection to the second board, only this one receive the connection request.

[Jørgen Holmefjord]

I assume the peripherals are not configured with the same address? Are you sure the BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST event are generated by the connection to the second device? How are you handling this event? Could it be that your laptop does not support higher ATT MTU and will not send this request, which would explain why it works on the laptop?

[StephaneJ]

Hi Jørgen,

The peripherals doesn't have the same MAC address on nRF Connect (I suppose this is the MAC address). Yes I'm sure this event is generated by the connection of the second device. I'm not handling this event, I just show that it happen when I put my board in DEBUG mode.

How can I know for my laptop ? I'm on a Macbook macOS High Sierra 10.13.3.

What does it mean exactly "not supporting higher ATT MTU" ?

Thanks

[Jørgen Holmefjord]

You should handle the event, as described on this page. Could you provide a sniffer trace of what is sendt on air, so we can see which requests are sendt where? Could you also upload the project or an example application that can be used to reproduce this issue?