Mesh low power current consumption

RE: Mesh low power current consumption

Hung Bui — Tue, 16 Jul 2019 08:48:14 GMT

Hi Gerry,

You would need to disable the mesh stack and put the device to sleep. When you wake up, you need to initialize the mesh stack again.

There is a bug in the stack that disabling it may take longer time that it should. You can follow this case: https://devzone.nordicsemi.com/f/nordic-q-a/43301/nrf_mesh_disable-function-changed-since-sdk-for-mesh-v3-1-0/180061#180061

RE: Mesh low power current consumption

Gerry — Tue, 16 Jul 2019 08:31:47 GMT

Thanks for that. The "Low duty cycle node" described in this document, is exactly what we want to achive.

We tried already, but in a mainloop like this:

    for (;;)
    {
        (void)sd_app_evt_wait();
    }

we always loop, meaning, the program comes out of sd_app_evt_wait() multiple times per second. I would expect, the program to stay in this function, until an external- or RTC-interrupt occurs. We already tried with nrf_mesh_disable() and scanner_radio_stop() but this didn't help.

Could you give us some lines of code, to see how this "Low duty cycle node" would be achived in the light switch server example?

RE: Mesh low power current consumption

Hung Bui — Mon, 15 Jul 2019 14:55:07 GMT

The poll timeout is configured in the LPN example with POLL_TIMEOUT_MS. It's set to 10s by default, you can try to increase this.

There are actually other options to do low power with mesh. One of them is just to simply put the device to sleep mode and wake up when need to send something. You can sleep for up to 96 hours.
I attached here a slides we used in a conference in Bluetooth World 2018. Please have a look. This slides are not for redistribution.

devzone.nordicsemi.com/.../LowpowerMesh.pdf

RE: Mesh low power current consumption

Gerry — Mon, 15 Jul 2019 12:35:24 GMT

Hi Hung,

Our low power node needs to send data only. (for example once every 5 minutes)

The average current of the LPN is 40uA now (without changing the example). Where can we change the poll timeout and what functionality will it affect?

Since there seems to be no difference in average power consumption whether a friendnode is connected or not, we would be interested in having our light-switch-server based application to consume as little current as possible (without having a frindnode). I can not see, where this is made in the LPN-example. Our light-switch-server based application consumes 10mA at the moment.

Regards

Gerry

RE: Mesh low power current consumption

Hung Bui — Mon, 15 Jul 2019 11:50:11 GMT

Hi Gerry,

What is your current average current consumption ? Note that depends on the Poll timeout, how often do you wake up and send/receive message, you may have different power consumption levels.

Note that the sleep current of a LPN can get down to 3uA in our test here.

Does your node need to receive data from other nodes ? or it only needs to send data ?