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Matter - fastest time from power up to first detected Event?

AMarch

We have implemented a simple contact switch using the nrf52840 and the latest zip generator (v99). The device connects to a Samsung Smart things edge router. A contact device shows up in the application and pressing button 2 makes the device close on the screen. I was able to script closures into turning on lamps. So that appears "functional".

What I was hoping I could find information about is the length of time a device needs to contact the router and be detected, from a power off state. 
Some testing has shown it can take a very long time. The test is generally holing the switch down and powering on the device. The power profiler shows what appears to be continuous transmission of the button state, however the application can take a minute to finally detect it.

Is there a known set of configuration values that allow the device to inform the edge router that it is not just intermittent but when it does come on it needs to be configured ASAP? 

I am very sorry that I do not know the proper MATTER/Thread terminology here.

Does the 32Khz crystal allow the device to be detected faster? 

  • 0 in reply to Sigurd Hellesvik
    AMarch said:
    the end goal is to have a device that is not only in low power mode but essentially off.

    For a sanity check here: What is your expected "sleep times"  here?
    What you describe is only power-efficient if you sleep long enough. Since powering on and off uses a lot more current than toggling low power modes, it is only recommended for sufficiently long off-periods

  • 0 in reply to Sigurd Hellesvik

    Ok, a long delay here while I circle around to this project again. It looks like we could be sleeping for up to an hour. 

  • 0 in reply to AMarch

    Hi,

    You will not gain much from powering the device off completely compared to being in idle mode when it is off or sleeping for just an hour. Reconnecting to the networks and re-establishing all Matter CASE sessions after reboot consumes a lot of power compared to simply waking up from sleep.

    If the device is supposed to be activated on button press, the latency will also be relatively high. It might require several seconds, or even a minute if the device needs to reattach to a different Thread parent, before the device is ready to transmit, which will significantly impact the user experience.

    The best option is to use SED/SSED and long idle time (LIT). As you mentioned, LIT is not currently fully supported, but it will be supported in a later version of the nRF Connect SDK.

    Best regards,
    Marte

  • 0 in reply to Marte Myrvold

    In our case power off isn't so much a power saving mode as a general power up condition. Like something being charged by a solar cell. Sometimes it will have power, sometimes it will come online after gaining power and MUST report its current status as soon as possible.

  • +1 in reply to AMarch

    Hi,

    Thank you for clarifying. Unfortunately, connecting to the network will take a few seconds, or possibly minutes, with the current implementation of Matter. The ICD Management Cluster and Long Idle Time might improve this when it is fully supported, but my suspicion is that you will still notice a delay since the device needs to initialize the radio and connect to the Thread network.

    As stated previously, the best option to send something immediately when the device is ready is to use the Thread state in ChipEventHandler().

    Best regards,
    Marte

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