Prioritizing outgoing data from BLE peripheral depending on bandwidth?

RE: Prioritizing outgoing data from BLE peripheral depending on bandwidth?

Kenneth — Tue, 20 Feb 2024 14:41:35 GMT

I suggest to make this very simple, just have some global flag that when set stop feeding the low priority data to the BLE stack, then only when you have sent the high priority data you clear the flag to resume feeding the low priority data again. As long a you have a short connection interval then any low priority data in the BLE buffer will in any case be emptied in (worst case) few connection interval.

Kenneth

RE: Prioritizing outgoing data from BLE peripheral depending on bandwidth?

pertan — Tue, 20 Feb 2024 12:23:55 GMT

Hi Kenneth,

thanks for you quick reply.

One thing that I failed to mention is that the low priority data consists of sensor value samples. It is acceptable to discard outgoing samples when needed and only write these to the BLE stack if the bandwidth is high enough. The scenario I want to avoid is low priority sensor data clogging up the output buffers and preventing/delaying the delivery of high priority data. On the other hand, I'd like to utilize as much available bandwidth as possible.

RE: Prioritizing outgoing data from BLE peripheral depending on bandwidth?

Kenneth — Tue, 20 Feb 2024 11:50:02 GMT

Hello,

Once a notification have been written to the BLE stack, it will be sent in the order they are written from the application. So the only thing you can control here is the order notifications are written from the application. That said though, I am not entirely sure how big of a problem this really is, a lot of packet can be sent, and typically the buffers are emptied between connection events (e.g. connection intervals). So the best way to ensure you can send data with short latency is to always use a short connection interval.

[quote user=""]I'm using a large MTU to maximize throughput. [/quote]

Make sure that you also have DLE enabled (e.g. DLE size >= ATT MTU + 3bytes), else that ATT MTU may be fragmented on-air, and you don't really get any benefit of using larger MTU.

Kenneth

RE: Prioritizing outgoing data from BLE peripheral depending on bandwidth?

pertan — Tue, 20 Feb 2024 11:45:18 GMT

Edit: looks like radio notification link is dead. Here's a working one: devzone.nordicsemi.com/.../optimizing-ble-midi-with-regards-to-timing-1293631358