Low data rate when connected to multiple sensors

[Adam W]

Hello,

I have 9 sensors based on NRF54L15 working as GATT server. I push around 100 bytes every 15ms from all sensors to the central hub. When i connect all nine of them to the central hub, some of them (usually one or two) start to "lag" (i can see lower data refresh rate on the dashboard). It does not happen every time, sometimes the system works as expected. I increased the MTU size to 251. I also loged the communication with wireshark and this is the output:

Should the timing look like this? I dont know why there are up to four packets bundled together (is this due to MTU size?). Or maybe the root cause of the "lag" issue is somewhere else? Thank you for any help

[Benjamin]

Hi Adam,
My first thought is that a 15 ms period isn’t sufficient for transmitting 100 bytes from 9 sensors. Our Online Power Profiler Tool shows an event length of 1.76 ms, which totals 15.84 ms, too long for the required timing.

Could you please provide a sniffer trace between your central device and one of the sensors?

Best regards,
Benjamin

[Adam W]

I played around with connection interval and got a better result in data rate. I also discovered that a data batching is a thing so for now the issues seems to be resolved (or more understood at least). Thanks for help.