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  • Case ID: 299048
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PSM floor current is 60uA not 4uA

Frikkie Badenhorst

Hi there, 

We are running a power consumption test using PSM mode, and we are however not measuring the 4uA floor current as expected.

We are requesting a active time of 6 minutes, and TAU time of 30minutes. We are also using eDRX.

However after the active time has passed, the device does not go into a low power state. There also appears to be a lot of noise:

I can confirm that the network does assign us the correct timers, as we get the following message in:

+CEREG: 1,"0001","01A2D002",7,,,"00100110","11100000"

Kindly advise what can be the issue here?

  • 0 in reply to Achim Kraus
    Achim Kraus said:
    4: using eDRX and PSM together doesn't work as expected.

    I have not seen any issues with the modem itself, related to current consumption in PSM. eDRX (RRC idle) is part of the PSM request. It will stay in eDRX during the "active time" before entering PSM and is a very common use case. The problem is most likely in the application.

    I tried the NCS 1.9.0 version of the application, and I had to specifically change uart2 status to "disabled" in order to get the current down. This was the only change necessary. Unfortunately I was not able to get the NCS 1.8.0 version to run, it's just crashing during boot, and I will have to investigate why this happens. Anyways, 1.8.0 is quite old now so it would be great if you could try out a newer version of NCS.

    By the way, I see that you are using the PPK. A new PPK firmware update was released today that was targeting issues with showing the idle current correctly when the current is drawn in bursts, which is often the case with buck/boost converters implementing burst mode. The reported idle current was higher than the actual current consumption. This is now fixed. Although I understand that this is probably not the case here since the hex-file I created earlier did show the correct current consumption. Just wanted to mention it. The PPK firmware will be updated automatically when the PPK software is updated through nRF connect for desktop.

  • 0 in reply to Stian Røed Hafskjold

    > By the way, I see that you are using the PPK. A new PPK firmware update was released today

    Great. I will do that tomorrow.

    I don't use eDRX and I'm also not aware of any issues in PSM without eDRX. Therefore I mentioned "4" just in the case, that 1 and 2 are also not responsible for the larger current. We will see, if verifying 1 and 2 already answers the topic.

    What may speedup this topic would be a prebuild "serial LTE modem". I guess using that with the AT/modem settings applied by Frikkie should give some more answers.

  • 0 in reply to Achim Kraus

    Hi,

     let us know the results of your testing.

    Best regards,
    Dejan

  • 0 in reply to dejans

    Hi all,

    Apologies for the delay in response - we had other priorities to attend to first. However, looking forward to get back onto this and solve it as we think PSM might be a feature that we can use. (We are still considering PSM vs just turning the modem of completely).

    Anyways, we have also manually disabled the uarts and will start testing with it, hopefully it solves the issue. 

    Will keep you updated.

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