NRF52840+Zephyr + SoftDevice S140 - Does flash access for NVS need to be managed by direct softdevice api access?

[JustinL]

Hi,

I am using Zephyr configured to use the softdevice as the BLE controller. 

I am looking to read and write a small amount of data to the flash for non-volatile storage. 

I have seen multiple support threads suggesting that when using a softdevice, flash access should be handled via the softdevice to ensure no conflict with radio activity.

Is this the case with Zephyr with softdevice configured? Or are all the examples softdevice safe by default?

i.e. could you clarify which non-volatile storage APIs can be safely used to write to flash on nrf52840 whilst BLE radio activity is ongoing via softdevice control.

Thanks in advance.

[Susheel Nuguru]

Hi,

In Zephyr all non volatile memory access makes sure that it schedules the flash operation in between the radio events. 

In short, you can still call the non volatile API at any time and the internal implementation of that API will make sure that the operation works safely when BLE is enabled.

[JustinL]

Great!!

Thanks

[davege]

Hello everyone,

I came across this question while looking for exactly the same detail.

We are implementing an application based on Nordic Connect SDK v1.7.0 for nRF52840 chip, and using SoftDevice Controller for BLE.

The documentation on nrfxlib states that NVMC shall be accessed only via the SoC API provided (here https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrfxlib/softdevice_controller/doc/api.html#softdevice-controller-soc).

Susheel Nuguru can you please confirm that, in case of non bare-metal application, we can directly use standard NVS API from Zephyr to write to Flash?

Do you think we can either use NVS backend API(https://docs.zephyrproject.org/latest/reference/storage/nvs/nvs.html) or the Settings subsystem API(https://docs.zephyrproject.org/latest/reference/settings/index.html) without any risk of conflict with Radio activity?

Thanks a lot.

D

[davege]

Susheel Nuguru could you please follow-up here?

It would be great to have a confirm, thanks a lot!

D