KE18F FlexRAM EEPROM Back Up

[sean_dvorscak]

I am wondering how the FTFE backups data from FlexNVM that is used for EEPROM.

1.) If I write to one location in the FlexRAM area, will the entire block of FlexRAM that is partitioned for EEPROM be backed up, or will just what I wrote be backed up?

2.) Will it also backup every time that I write to the FlexRAM area, or does it periodically back it up?

[kerryzhou]

Hi sean_dvorscak,

Answer your two questions:

1.) If I write to one location in the FlexRAM area, will the entire block of FlexRAM that is partitioned for EEPROM be backed up, or will just what I wrote be backed up?

Answer: No, just your wrote be backed up. Please note, the EEPROM backup is also the flash, as you know, the flash has endurance, so it won't write the not used data, just to save the endurance.

2.) Will it also backup every time that I write to the FlexRAM area, or does it periodically back it up?

Answer: Just when you write to the flexRAM area, it will be back up, it won't periodically back.

You also can refer to this post:

https://community.nxp.com/t5/Kinetis-Microcontrollers/FlexNVM-and-EEEPROM-Functionality-Clarificatio...

Which I share some of the eeprom code.

Wish it helps you!

Best Regards,

Kerry

[sean_dvorscak]

Hi kerryzhou,

Thanks for clarifying that.

I have 2 new questions for you.

1. When writing data to FlexRAM is there a possibility of a partial or corrupted writes to backup EEPROM if a power interruption occurs during the time the file system is writing to backup EEPROM?
2. I would like to understand the 50% reduction in endurance when performing 8-bit writes to FlexRAM compared to 16-bit or 32-bit writes. Is this reduction independent of the number or writes performed? In other words, according to the data sheet with an EEPROM backup to FlexRAM ratio = 16, the write endurance would be 140k writes minimum for 16-bit or 32-bit writes, but only 70k for 8-bit writes? What accounts for this?

[kerryzhou]

Hi sean_dvorscak,

   Please read this application note, it will be more clear:

   https://www.nxp.com/docs/en/application-note/AN4282.pdf

1. When writing data to FlexRAM is there a possibility of a partial or corrupted writes to backup EEPROM if a power interruption occurs during the time the file system is writing to backup EEPROM?

Answer: Please check the AN content:

2. I would like to understand the 50% reduction in endurance when performing 8-bit writes to FlexRAM compared to 16-bit or 32-bit writes. Is this reduction independent of the number or writes performed? In other words, according to the data sheet with an EEPROM backup to FlexRAM ratio = 16, the write endurance would be 140k writes minimum for 16-bit or 32-bit writes, but only 70k for 8-bit writes? What accounts for this?

Answer: about the endurance, totally determined by the formula:

My understand is 8-bit eeprom, to the flash, each write may cause more load, then the efficiency is smaller than the 32bit, it is the chip design feature, and can't be modified, so if you can use 32bit or 16 bit writes, it's better not use the 8 bit, just to get large endurance.

Wish it helps you!

Best Regards,

Kerry