Server Publishing messages every minute

RE: Server Publishing messages every minute

Hung Bui — Wed, 13 May 2020 08:57:23 GMT

Yes, your understanding is correct. The friend node has to be main powered.

But I'm not sure why you need a mesh network if your network is comprised of only a "central" node and a few "server" nodes that inside the central's range. It's a star network and you can easily do it with normal Bluetooth Low Energy. This would make it much more simple. And the client/central node can run on low energy as well.

RE: Server Publishing messages every minute

nish — Wed, 13 May 2020 07:04:24 GMT

Hi Hung,

I have been reading on the LPN feature and network topology that include LPN's & normal nodes.

From my understanding, in order to use the LPN feature, you are required to have a Friend node. This friend node can for example be the light switch server example , does this mean that the friend node will be permanently powered?

In my use case, I actually have one Client node and three servers nodes. All nodes are supposed to run off a battery and should be sleeping and wake up periodically to send a message to the client.

If I understand correctly, in order to use LPN feature, I will need one friend node that is permanently powered and that friend node has a friendship with each server node as well as the client node.
Please advise if this is the correct network topology for my use case?

Thanks.

RE: Server Publishing messages every minute

Hung Bui — Mon, 04 May 2020 14:33:58 GMT

Hi Nishant,

From SDK v4.1 LPN has been pulled out of experimental.
When it's experimental it meant that it's not fully tested and not qualified. But please use the latest SDK v4.1 if possible.

RE: Server Publishing messages every minute

nish — Thu, 30 Apr 2020 12:43:57 GMT

Thanks Hung,

I initially started from the Light Switch example and have built my firmware a long way from there.
My question is, that i see the LPN has only an "experimental" example. What exactly would be involved to now convert my project to use LPN instead of normal?

RE: Server Publishing messages every minute

Hung Bui — Thu, 30 Apr 2020 12:30:21 GMT

That can help a little bit as the sequence number will not be increased on each reset a NETWORK_SEQNUM_FLASH_BLOCK_SIZE. But it will still end up in the same situation if you don't keep the device long enough to receive and perform IV index update.

If you plan to have the device running on battery, you should use set it up as LPN node instead of normal node.

I'm still waiting for the reply from our team.

RE: Server Publishing messages every minute

nish — Wed, 29 Apr 2020 11:17:02 GMT

Hi Hung,

Since the mesh node should stay powered all teh time, Would calling nrf_mesh_disable() and then putting the NRF to sleep (as opposed to power off), and then wake up from external interrupt and nrf_mesh_enable() work? Will the NRF do a chip reset on wake up? or will it continue from where it went to sleep?

Thus hopefully meaning the chip will not reset, and hence the sequence number will not reach the maximum so quickly?

RE: Server Publishing messages every minute

nish — Wed, 29 Apr 2020 10:05:53 GMT

Hi Hung,

I am using Mesh SDK 3.2.0 and nRF5_SDK_15.3.0_59ac345.
In our application we are running our device off a battery and thus require to unpower the NRF52 MCU to preserve battery.

I shall await for further feedback from you .

Thanks

RE: Server Publishing messages every minute

Hung Bui — Wed, 29 Apr 2020 09:47:29 GMT

Hi NIshant,

Could you let me know the SDK version you are using ?

The reason you are getting this issue is that the IV update was not performed resulting in the sequence number reached max sequence number. And the root cause was that your device was sleeping most of the time and didn't catch or didn't perform an IV index update.

Normally a mesh node is designed to stay active and listen all the time. For your use, a LPN node is a better solution.

I'm checking with the team to see what would be the best solution for this.