FATAL ERROR using NVS for writing to flash while BLE is active

RE: FATAL ERROR using NVS for writing to flash while BLE is active

V.Lorz — Sat, 28 Oct 2023 15:24:01 GMT

Sigurd, thanks for your support, it guided me to look at the right place.

I needed to explicitly set CONFIG_SOC_FLASH_NRF_RADIO_SYNC_NONE=n, and found out that the effective chain of calls until it arrived to the driver's flash write function required a much larger stack for the work queue.

I already had a work thread for low priority tasks with a suitable stack size and deferred the flash write operation to that thread instead of adding more RAM usage to the application.

Thanks again, BR

RE: FATAL ERROR using NVS for writing to flash while BLE is active

Sigurd Hellesvik — Thu, 26 Oct 2023 10:42:50 GMT

Aha, yea no then it should not matter that it is called from a callback I think.

The NVS drivers use the flash API, which is defined for nrf here.

[quote user="V.Lorz"]BLE has very tight timing requirements, so flash operations MUST be executed synchronized with its operation.[/quote]

You are right, and this is already taken into account in our SDK, as long as CONFIG_SOC_FLASH_NRF_RADIO_SYNC_NONE is not set. You can see how this is handled in the flash write driver.

Can you check this option for your project?

RE: FATAL ERROR using NVS for writing to flash while BLE is active

V.Lorz — Wed, 25 Oct 2023 19:33:43 GMT

One thing to note here is the callback function is not called from inside an ISR context, but from a work thread. Zephyr does that for us, which is nice and convenient.

Of course I can enqueue the job for later, but I can still face the same issue at random because the origin is BLE has very tight timing requirements, so flash operations MUST be executed synchronized with its operation.

Question remains the same: How can I achieve that?

RE: FATAL ERROR using NVS for writing to flash while BLE is active

Sigurd Hellesvik — Tue, 24 Oct 2023 06:42:49 GMT

I recommend not calling NVS functions from a callback.

Instead, either do it the easy way and set a global variable that you poll in a thread somewhere.
Or, do it the more clean way and use a work queue which you trigger from the callback.

RE: FATAL ERROR using NVS for writing to flash while BLE is active

V.Lorz — Mon, 23 Oct 2023 14:21:32 GMT

Hi,

Yes, I do, I write to NVS "inside the callback that handles a characteristic write."

The test I mentioned that works OK is writing/reading before initializing BLE.

RE: FATAL ERROR using NVS for writing to flash while BLE is active

Sigurd Hellesvik — Mon, 23 Oct 2023 11:40:29 GMT

Do you by chance write to NVS from a BLE callback?

If not, can you explain a bit on how you test writing to NVS while BLE is on?

Regards,
Sigurd Hellesvik