Synchronizing Actuation of Low Power Bluetooth Mesh Nodes

RE: Synchronizing Actuation of Low Power Bluetooth Mesh Nodes

Amanda Hsieh — Wed, 20 Aug 2025 16:56:17 GMT

Yes, your understanding is correct.

RE: Synchronizing Actuation of Low Power Bluetooth Mesh Nodes

barbiz — Wed, 20 Aug 2025 16:05:59 GMT

Hello Amanda,

thanks for your answer.

I was furtherly thinking. Even with a Scheduler Server and Time Model, the protocol itself is not aware of the propagation delay across nodes, so it will never be able to syncronize better than the propagation delay. Does this sound correct to you?

Thanks

Marco

RE: Synchronizing Actuation of Low Power Bluetooth Mesh Nodes

Amanda Hsieh — Wed, 20 Aug 2025 16:02:35 GMT

Hi,

[quote user=""]How can I make sure all low-power light nodes switch simultaneously when triggered by the switch? Is there a recommended approach for achieving synchronization in Bluetooth Mesh with low-power nodes?[/quote]

LPN - Friend communication is always reduced till p2p communication between them, which includes randomness by self. Even more, if a couple of LPNs have the same Friend, they will compete during communication and collide with each other with frequent polling that will add random desynchronization among them.

The only way to reach synchronousness is to spread a turning-on message over broadcast (multicast) within 1 hop (not for LPN) or using a Scheduler Server instead. You can send a scheduled event to set the OnOff state at an exact time on all devices. It will work only if time is synchronized among devices (read details in the Scheduler and Time models documentation).

[quote user="barbiz"]Is this a wanted behavior? I was thinking that BLE MES was able to execute synchronized commands.[/quote]

This is expected. BLE Mesh does not provide true synchronized execution of commands across nodes, even for always-on nodes, and even when using transition delays.

Regards,
Amanda H.

RE: Synchronizing Actuation of Low Power Bluetooth Mesh Nodes

barbiz — Wed, 20 Aug 2025 13:36:18 GMT

Actually, we were able to measure that even the normal (non low power) nodes do not executed synchronized commands when the command is relayed in the mesh.

TX -> node1 -> node2

Where node2 is not in range of TX.

Then, even applying the delay to the SET message, node1 and node 2 do not execute the command in sync.

Is this a wanted behavior? I was thinking that BLE MES was able to execute synchronized commands.