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Low power mesh node

Posted: Thu Aug 15, 2019 12:53 pm
by seypa3
Hello,

I have a question about using the mesh for a battery powered node.
Why I want to use wifi mesh instead of ble mesh:
I need to transfer relatively "large" data/file (around 500kB) for 4 - 5 times a day to my node.
To check if new data is available the node will wake up every 15min and connects to a server via MQTT.
My problem is now the 15min wake-up. Even configured as leaf node it takes around 3-4 seconds. Which quickly will draw the battery.
esp-now will be possibility but then I somehow loose the mesh advantages.
I looks like there shall be some low power features for the wifi mesh but I cannot find more information about it.

Has anybody an advice about the best setup for my use-case?

Re: Low power mesh node

Posted: Fri Aug 16, 2019 1:00 pm
by ESP_LBB
Hi seypa3,

In this case, we still suggest ESP-NOW for this battery powered node, it's the way that can save more energy (could you tell the battery capacity), when there is no need to send data we can put the node into deep sleep mode and only ULP works, and wakeup and send data via ESP-NOW. Other nodes which have power supply can work in ESP-MESH mode to extend the network. In this mode we still have the advantage of mesh. Sure you can put the node to work as mesh node, but as you said, it will take several seconds more to join the network.

We are testing light sleep mode for mesh network (except for root) but we don't believe it can work with battery for long term.

Re: Low power mesh node

Posted: Fri Aug 23, 2019 2:08 pm
by seypa3
Hello,

thanks for the reply.
The battery will have 2000mA
Is it possible to combine mesh and esp-now?
The disadvantage I see with using esp-now is that I have to connect the battery driven esp-now node manually with the neighbouring mesh node with best signal strength. Is it possible to automate it so that the battery node is searching for the best mesh node connect to it and also stores that information for the next time to speed up the process?

Re: Low power mesh node

Posted: Mon Aug 26, 2019 1:46 pm
by it_zzc
esp-mdf's [button_example]https://github.com/espressif/esp-mdf/tr ... kit/button is using this solution,
1. The button first selects the parent node and binds in esp-mesh module
2. Then enters the espnow mode to send the packet to the device, and the whole process(waking up > send > sleep) can be controlled within 1 second.