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NRF52840 Thread example power down 10 mins after USB disconnect

meetandyhere

Hello,

I am trying the Thread Cloud COAP Client

<InstallFolder>\examples\thread\experimental\cloud_coap_client

on a NRF52840 PDK. I'm using Thread SDK v0.10.0. The example works as described.

However, when I unplug the board from USB, it goes into some kind of power down mode in approx. 10 minutes and loses connection to the Thread network. I can see LED1 is still on, but it is extremely faint. It is flickering, so trying to connect to the network, but it cannot do so. After a further 5-6 minutes of this, LED1 goes completely off.

I had a few questions about this behaviour:

  1. Where in the code can I set the time between USB disconnect and going in power-down mode?
  2. I know that the NRF52840 has System ON and System OFF power modes. Where in the code can I set which mode it should go in?
  3. Is the behaviour of it not being able to connect to the Thread network when in low power mode expected? If so, can I change this behaviour or is there a fix planned?

Thanks in advance!

Regards

Andy

  • 0

    How is the board powered when you unplug it from the USB? Could it be a battery issue?

  • 0

    The board is powered by a CR2032 battery that came when we purchased the kit. It doesn't seem a battery issue because the board is powered on and works well for about 10 mins after USB disconnect. After a subsequent USB connect and disconnect, we get the same behavior. So there seems to be some pattern with the 10 min power down behavior. Also, non-Thread BLE examples, e.g. HRM from the SDK v. 13.1 run for much longer than 10 mins on battery. So I was wondering if it is some Thread-specific issue?

  • 0

    And you are using the same battery for every test? And this does not happen after 10 minutes if you power it from USB? Sounds really strange, but I'll look into it. The Thread examples would be much more power hungry than for example HRM, because it will almost be scanning all the time.

  • 0

    Yes, I am using the same battery for every test. If the board is connected to USB, it works uninterrupted without any power down. Is the power consumption of Thread examples quantified? We are interested in using Thread for further development, but a big constraint for us is that battery consumption should be minimal. Our use-case is a door sensor which sends door open/close information when this status changes to a cloud application. The Thread Cloud CoAP client seems to be a straightforward solution, but maybe we have to rethink using Thread if it consumes too much power. Could you recommend a non-Thread example which can achieve the similar Client-Cloud functionality as the Thread example?

  • 0

    Strange. Could it be that you are draining too much current from the battery, but I'm not sure if there is anything special happening after 10 minutes. Is it exactly ten minutes? Have you tried to measure the current consumption?

    If the power consumption of the Thread examples are quantified? I'm not sure what you mean by this. The thread router role is not very battery friendly as it is scanning most of the time. If you want to run of a battery you should look into the sleepy end device. Maybe you can use that?

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