How big is the event buffer of the SoftDevice

[Marius Heil]

Hello,

I am using am using sd_ble_evt_get and sd_app_evt_wait in an endless loop for handling all incoming events. If I block this loop from executing, I'd expect that some events are lost at one point. So my question is, how big is the event buffer of the SoftDevice? And what happens if my application logic takes too long to process an event. Will events get lost?

Thanks

[Wojtek]

I don't know abput buffer, but why don't you use scheduler to buffer those events? You can change scheduler queue size in app.

[Marius Heil]

Hello,

that's the way I'm doing event handling right now and it works, so I don't want to change it right now without any reason to do so. It's one of the proposed methods of the nordic SDK.

[Anders Strand]

Hello.

For the Softdevice S130, it is 6 events per link. If this buffer is full, the softdevice will start NACK'ing incoming BLE packets. These packets will be retransmitted until they are successfully sent. They will therefore not be lost.

-Anders

[Marius Heil]

What happens with other events? Say: The Softdevice received 6 packets and its buffers are full, afterwards, the link is disconnected. Will the disconnect event be lost? And what about events such as incoming advertising data that do not directly belong to a link?

[Anders Strand]

The disconnect will also be retransmitted by the initiator a certain amount of times. If it cannot get the disconnect packet through, it will time out and just drop the connection. In your end, you will then never receive the disconnect, but receive a supervision timout on the connection. The incoming advertisements will be lost if all event buffers are full. I am not sure if a separate event buffer is set only for advertising though.