Best approach to save data to flash while using Softdevice

[AqibK]

Hello,

I am using  nrf52840, SDK 17.0.2, softdevice s140 and also implemented OTA DFU in my application.

I want to save some data lets say admin code in flash. Once I burn the firmware to device it should be like below

 uint8_t ADMIN_CODE[6]  = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};

During my application is running I want to change it to lets say ADMIN_CODE[6]  = {0x12, 0x56,0xFF,0xAA,0xFA,0xCD}. Then this becomes my admin code and when I power off and back on my ADMIN_CODE[6] should not go back to {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF} but instead should remain same ie: {0x12, 0x56,0xFF,0xAA,0xFA,0xCD} And when I do reset then it should go back to  {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF}.

I saw some questions like this already on forum, some suggested to use flash write using NVMC or UICR and some suggests to use pstorage or FDS. I am confused what is the best approach in my scenario. Also if you can guide to some example code of right approach, that would be great!

[Hung Bui]

It's not automatically done when you do a reset. 
If you want to do that you need to implement the code on your own, for example when you booting up you can check the RESETREAS register if it's booting up from a pin reset or not. Do something like this: 

if (NRF_POWER->RESETREAS & POWER_RESETREAS_RESETPIN_Msk)

{

//It was booting up by pin reset

}

[AqibK]

Yes, now its working as intended. Thank you Hung Bui!