Reducing power usage of the Light Switch Server

[SamTheMan]

Hello everybody,

I'm currently trying to create a Bluetooth Low Energy Mesh network of multiple nodes that I can control using a Bridge application.

I use a nRF52840 DK with the Serial Example (PyACI) for my Bridge and the nRF52840 DK's loaded up with the Light Switch Server example for my nodes.

Now my system seems to be working fine (With the bridge I can provision and turn nodes off/on remotely), however when I measure a node's current using the Power Profiler Kit 2 I get a power consumption average of ~13mA when not sending messages and ~15mA when receiving messages.

After more investigating this seems to be so, because the nodes are constantly scanning for messages, which seems to consume ~10mA and the BM-LPN node example seems to consume roughly 8mA?

Is there a way to reduce the power consumption of my nodes to be within the µA range if they're not sending messages?

Cheers,

Sam

[SamTheMan]

Hi Hung Bui,

 

"Each BLE node can handle up to 20 connections at the same time."

Do you mean in-general for the Bluetooth specifications? Because it looks like the nRF52840 DK board loaded with the 'light switch server example' can only handle 2 friendships from "LPN Client node example" at the same time.

I get the NRF_ERROR_NO_MEM error whenever I try to establish a 3th friendship to a single Friend node (first 2 friendships establish successfully).

So I read on webpage https://www.bluetooth.com/blog/bluetooth-mesh-networking-series-friendship/

"The amount of RAM available directly affects how many LPNs a Friend node can support and how many messages it can buffer for associated LPNs." 

Which makes me believe the nRF52840DK boards have only enough RAM to handle 2 friendships at the same time. Is this correct? Or is there a setting I can change to be able to add more nodes?

 

I've managed to set up a good working network; Although that would be my only restriction at the moment.

 

Cheers and thanks for the help,

Sam

[Hung Bui]

Hi Sam, 
I was talking about normal BLE- Bluetooth Low Energy, not mesh. If the network is not large (more than 20-30 nodes) and can be covered by 2-3 central nodes then it's possible to not use mesh at all and only use BLE. This way both the centrals (backbone nodes) and the peripheral (edge nodes) can be low power. 

If you prefer to use mesh, you can increase the friend capacity by defining: MESH_FRIEND_FRIENDSHIP_COUNT in nrf_mesh_config_app.h  . By default it's 2.