BLE: Too many notifications lead to disconnect

Hi there,

I use a Raspberry Pi 3 as peripheral and have a characteristic which users can be notified with.

Everything works quite well but when I call

service->writeCharacteristic(characteristic, value);

too often (about 370 packets à 20 bytes in several seconds), the QLowEnergyController emits NetworkErrors, does not send any packets anymore to the central device and switches to UnconnectedState.

With activated logging, here's what I can see:

....
qt.bluetooth.bluez: sending notification/indication: "1b0300000000b95774d391746573744465760000000000"
qt.bluetooth.bluez: sending notification/indication: "1b03000000000062746c65737070000000746b6e000000"
qt.bluetooth.bluez: Cannot write L2CP packet: "1b03000000000062746c65737070000000746b6e000000" "Network Error"
qt.bluetooth.bluez: Network IO error while talking to LE device

(now the controller state changes to UnconnectedState and emits NetworkError messages)

qt.bluetooth.bluez: HCI event triggered, type: 13

This last HCI event repeats until the central device closes the connection.

From what I know, the number of packets per time depends on the connection interval and the number of packets that a device can send within a connection interval. This is confirmed by my observation that everything's fine if I wait 50ms after each packet.

The behavior I expect is either that if the stack can't keep the pace, I get an error, can wait a bit and then retry it. Though it would be better if writeCharacteristic would just block until the stack is available again.