Emteria Bluetooth Low Energy packet transfert size

Eric

I’m working with a BLE peripheral that require 150 bytes of packet transfert size.

1) Emteria doesn’t seem’s to enable the DLE feature in Bluetooth
(this is needed to send packet size of more than 20 bytes)

By sniffing the BLE packet : we can see in BLE message LL_FEATURE_REQ send by Emteria :
In the "Feature set" bitfield : the DLE (LE Data Packet Length extension) is set to 0
So, How do you enable this bit ?

Because of this, it’s not possible to switch the link layer to more than 20 bytes.
(and LL_LENGTH_REQ send by the peripheral will fail)

Any solution to switch to bigger packet size ?

2) The Emteria is the "central" BLE and should therefore send an MTU request, this is not done when connected to a peripheral ... any reason/explanation for that ?

Using a Rpi4 with Emteria OSv11.3.0

thanks,

Eric

bart

As an addition to my colleague Eric's post I'd like to say that in our application we call `BluetoothGatt.requestMtu(153)` after the GATT connection was made. We also successfully receive the `onMtuChanged(gatt: BluetoothGatt, mtu: Int, status: Int)` callback.

Also, when we used the Bluetooth sniffer with some Android smartphones the DLE bitfield is set to 1, while on the Rpi4 with Emteria it is 0.

smieschek

Hi @Eric and @bart
Thanks for the awesome question. Unfortunately, I don't have any answers for now. Gerrit will contact you for a meeting so that we can discuss your questions in detail.