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?

[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.

[ivnn]

What time delay you can recommend to wait for stabilize nrf52 after powerup ?
thx for reply!

[Einar Thorsrud]

I don't have a specific recommendation, but you should consider this in your particular case. The point is that ending up in a loop with rapid writes to flash is bad, and should be avoided. That is a general thing that is not particular to the nRF.

[ivnn]

Could POF warning help to block writing during power below threshold?

// Initialize SoftDevice.
err_code = sd_softdevice_enable(p_clock_lf_cfg, softdevice_fault_handler);
if (err_code != NRF_SUCCESS){
 return err_code;
}
err_code = sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE);
APP_ERROR_CHECK(err_code);
err_code = sd_power_pof_enable(1);
APP_ERROR_CHECK(err_code);
err_code = sd_power_pof_threshold_set(NRF_POWER_THRESHOLD_V28);
APP_ERROR_CHECK(err_code);

[Einar Thorsrud]

Hi,

Yes, flash writing is prevented when there is a POF warning condition. This is a bit odd though since it will look like the flash write operations succeed, but in fact, nothing is written to flash.

[ivnn]

I found an interesting condition it's happened if I have flashed bootloader

[Einar Thorsrud]

Let's continue here.