Disabling nRF5340 TrustedZone Protected Storage (explicitly, and during runtime)

[esmart-engineering]

In a previous version of my project, that did NOT utilize TrustedZone, I was using a persistent storage library (NVS) and noticed that adding/using it would increase the current draw (checked on a nRF5340DK using the PPK2). In this current version, which DOES utilize TrustedZone (PSA Protected Storage), I suspect that it is similarly drawing some additional current.

To that note, I have several questions:

• How do I explicitly disable PSA PS? I see in KConfig an option CONFIG_TFM_PARTITION_PROTECTED_STORAGE, but I'm getting build errors. Currently debugging it myself, but any places I should particularly look into?
• Can PSA PS be disabled during runtime? I recall that certain peripherals can be turned off/on during runtime (such as with NCS v2.5.0, zephyr\samples\subsys\pm\device_pm). Is there a similar mechanism available for this?

To summarize, my setup is using a Windows 10 machine, nRF5340DK, PPK2, NCS v2.5.0, a project in VS Code based on that NCS at path zephyr\samples\tfm_integration\psa_protected_storage

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EDIT #1 - I'm not as concerned whether it is truly drawing a lot of current or not. I just want to see how PSA PS can be disabled explicitly, and how to disable/enable it during runtime.

[Håkon Alseth]

Hi,

 

Having a filesystem should not automatically increase the current consumption, unless it is heavily used.

Can you share plots or info on how much you are consuming, and what you expect to consume?

 

The sample you're using has serial enabled, have you tried to disable it to see if this decreases the current?

https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/test_and_optimize/optimizing/power_general.html#disable_serial_logging

Since this is TFM, please ensure that CONFIG_TFM_LOG_LEVEL_SILENCE=y is set as well.

 

Kind regards,

Håkon

[esmart-engineering]

Sorry for the confusion. See my edit in the main post, but I currently am more interested in how to disable/enable PSA PS.

[Håkon Alseth]

Hi,

 

As mentioned, having a unused section or filesystem present shall not increase the current consumption.

Can you please elaborate on what is the cause of your added current consumption?

 

You can also have a look at the "build-folder/partition.yaml" to see how your flash is setup.

I just want to see how PSA PS can be disabled explicitly, and how to disable/enable it during runtime.

It is statically configurable, as per the kconfig that you initially mentioned.

  

Kind regards,

Håkon

[esmart-engineering]

Again, the current consumption issue is not really what I'm asking about anymore. Sorry for the confusion.

So is it impossible to dynamically configure PSA PS to be enabled/disabled?

[Håkon Alseth]

No, it is not run-time configurable.

 

Kind regards,

Håkon