Flash corruption caused by power down during writing

[Andrea Pieretti]

Hello,

I'm using nRF52840 chip with nRF5 SDK 15.2.0 ,Mesh SDK 3.1.0 and soft device S140 6.1.1

I'm trying to protect the flash if a shutdown occurs during a write.
Reading in the forum it seems that the POFWARN event does it for me.

I'm trying to configure this event but without success.
I use this code:

nrfx_power_config_t power_config = {.dcdcen = 1};
nrfx_power_init (& power_config);
nrfx_power_pofwarn_config_t pofwarn_config = {.thr = POWER_POFCON_THRESHOLD_V28,
                                                   .handler = power_failure_warn_handler};
nrfx_power_pof_init (& pofwarn_config);
nrfx_power_pof_enable (& pofwarn_config);

If I use this code snippet before enable the softdevice, the nrf_sdh_enable_request() return the NRF_ERROR_SDM_INCORRECT_INTERRUPT_CONFIGURATION error code

If I use this code after enable the softdevice, the program stops when it try to write the POWER->DCDCEN register

What am I doing wrong?

Besides this, what is the best practice to avoid flash corruption it a power off occours during a write operation?

[Einar Thorsrud]

Andrea Pieretti said:

How can avoid this issue for the SDK Mesh Flash Writes (for example, during the provisioning and subscribe/publish configuration phase from the provisioner)?

Usig POFWARN will prevent all flash writes. This is implemented in HW. From product specification:

If the power failure warning is enabled and the supply voltage is below the threshold, the power-fail comparator will prevent the NVMC from performing write operations to the flash.

[Andrea Pieretti]

ok thanks,

Now I see that, if the power loss occours during a flash erase, the NRF_EVT_POWER_FAILURE_WARNING event inside the SoC raises only after the erase complete.

The SDH_SOC_OBSERVER has already priority 0.

Is it possible to catch the NRF_EVT_POWER_FAILURE_WARNING during an erase operation?

[Einar Thorsrud]

No, that is not possible.

[ivnn]

Hi,

I have the same one problem, when I power up or perform power reset nrf52832 some times I have corrupted flash content.

Am I right I should add some code delay after powerup and before main code start?

[Einar Thorsrud]

Hi,

Not in general, but it is not a good idea to write to flash immediately after a reset since that could cause the device to go in a loop where it resets, tries to write to flash and get a power failure leading to a reset etc. if the battery is depleted.