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  • Case ID: 323486
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SIM shutdown does not happen during the e-DRX cycle greater than 60 seconds on NRF9151 DK

mnjLC

We recently got the NRF9151-DK and were trting to measure the e-DRX current on the system working on CAT-M1 network. The NRF9151 DK is loaded with Serial LTE Modem application ( Default application that it was shipped with )and Modem firmware v2.0.0 ( Default FW that it was shipped with ). According to this post we have set the follwing at commands 

at+cfun=0

AT%XDATAPRFL=0 // sets the low power mode

AT+SSRDA=0,1,0 // sim shut shutdown

at+cfun=1

at+cedrx=2,4,”0101”

We are still seeing 35uA of floor current during e-DRX cycle. We feel this is a bug in the pre lodaed FW. Can someone from nordic try it on their NRF9151-DK and share the results?. I all attaching the PPK2 trace with this post.

Thanks!

nrf9151_eDRX_80_PTW_1_1NCE_NoShutoff.ppk

Parents Reply Children
  • 0 in reply to mnjLC

    I don't think the form factor of the SIM affects anything.

  • 0 in reply to Didrik Rokhaug

    Hello Didrik,
    I'd first like to point out that the form factor does indeed make implications on the endurance capability of the NVRAM.  *Usually* MFF2 sims have a significantly higher endurance rating than their plastic counter parts. 

    We do have a question regarding suspend vs sim shutoff.  If your comment about wearing flash out applies even to proper implementations of the suspend command, that is an alarming concern.  There are a ton of factors here to consider for a physical SIM:

    • Endurance cycle, industrial MFF2 sims claim 500MM write cycles
    • Flash wear level implementation
    • Flash size (larger flash means less wear per cell if you have good wear leveling implemented)

    My point is that Nordic should have good answers to these questions.  I really request we get a full answer on this from the Nordic team.  I will in parallel ask our MVNO to also consider these points.

    The best solution would be a software SIM but I'm not getting any answers from my contacts at Nordic or our MVNO as to when that feature will be available.

    Thank you!

    -Patrick.

  • 0 in reply to papatel
    papatel said:
    I'd first like to point out that the form factor does indeed make implications on the endurance capability of the NVRAM.  *Usually* MFF2 sims have a significantly higher endurance rating than their plastic counter parts. 

    While MFF2 SIMs often have higher endurance ratings, my point is that there isn't, as far as I know, nothing inherent in the MFF2 form factor that makes it true. You can have plastic SIMs with high endurance rating, and MFF2s with low ratings.

    Any writing to flash will contribute to the flash wear, though as you say, there are many factors that contribute to how big of an issue this is.

    papatel said:
    The best solution would be a software SIM but I'm not getting any answers from my contacts at Nordic or our MVNO as to when that feature will be available.

    SoftSIM is been supported on the nRF9160 and nRF91x1 devices.

    I don't have a full overview of which operators are working on providing it, but at the moment, it is available from at least Onomondo and IIJ:

    https://onomondo.com/product/softsim-for-nordic-semiconductor/

    https://www.iij.ad.jp/en/news/pressrelease/2024/0226.html

  • 0 in reply to Didrik Rokhaug

    Hello Didrik,

    Thank you again for your response.  Given that SoftSim makes this feature obsolete and has several other advantages, I'd really appreciate candid updates on that front.  The community wants it yet there is so little information coming from Nordic on the subject.  If the strategy is to herd people toward using Onomondo, that is something we need to understand now.

  • 0 in reply to papatel
    papatel said:

    We do have a question regarding suspend vs sim shutoff.  If your comment about wearing flash out applies even to proper implementations of the suspend command, that is an alarming concern.  There are a ton of factors here to consider for a physical SIM:

    • Endurance cycle, industrial MFF2 sims claim 500MM write cycles
    • Flash wear level implementation
    • Flash size (larger flash means less wear per cell if you have good wear leveling implemented)

    Questions about flash wear leveling, etc. you have to take with the SIM card provider. That is SIM card internal functionality that our modem has no control over.

    I also checked with our SIM expert about why SIM cards does not allow deactivation. This was his response:

    "I’m not very well aware why deactivation is not allowed by many SIM cards. Haven’t heard card provider’s statements related to that.

    I suppose one reason could be concerns about toolkit application functionality. They get shut down and restarted every time when SIM card is deactivated/activated. Suspend is an improvement to that since it allows the SIM card to store it’s internal state before deactivation and continue from same situation after activation. It requires also implementation on SIM card side, and it looks like very few SIM cards have that done."

    papatel said:
    Given that SoftSim makes this feature obsolete and has several other advantages, I'd really appreciate candid updates on that front.  The community wants it yet there is so little information coming from Nordic on the subject.  If the strategy is to herd people toward using Onomondo, that is something we need to understand now.

    Can you be more specific about what information you think is missing?

    Questions about our roadmap should be taken to your local sales representative. I am not at liberty to discuss those details.

    Our interface SoftSIM interface should support SoftSIMs from any provider. However, it is up to each provider if they want to provide SoftSIMs, and what platforms to support. Onomondo is the first to be generally available (at least as far as I know), and information about their solution is also easily available, which is why they are usually used as the example.

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