Understanding FlexRAM Emulated EEPROM Data Retention Categories and the Effects of Writing Technique

[CarolJenkins]

I am utilizing the S32K146 FlexRAM as Emulated EEPROM and have a question regarding the "Data retention up to 100% of write endurance" category. Could you please clarify what this means exactly?

My understanding is that when the write endurance reaches 100% (i.e. when it is depleted and no more data can be written), any data previously stored on the emulated EEPROM can still be preserved for more than 5 years. Similarly, the "Data retention up to 10% of write endurance" category means that when only 10% of the write endurance has been used, the data stored on the emulated EEPROM can be safely preserved for more than 20 years.

For instance, I have set my chip EEPROM backup size to 65536 Bytes and FlexRAM EEPROM size to 4096 Bytes, resulting in an EEPROM backup to FlexRAM ratio of 16. Over the course of 10 years, the application would completely overwrite the emulated EEPROM 100k times. In this scenario, can the data that was last written to the emulated EEPROM be safely preserved for more than 5 years?

Furthermore, I am curious to know if the way I write to the emulated EEPROM affects its data retention. I am currently using Processor Expert and S32 SDK to operate the emulated EEPROM. Do I need to write data evenly throughout the EEPROM manually, or will the driver handle the optimization work? Your insights on this would be highly appreciated.

Thank you! 

[danielmartynek]

Hello @CarolJenkins,

Yes, that is all correct.

No need to write the data evenly throughout the EEPROM manually.

When a new record is written to the EEPROM, the state machine stores the record in the Backup Flash along with the address of the record in EEPROM. When an old record is updated, it moves the record to a new location in the Backup Flash again with the address of the record in the EEPROM and it invalidates the old record. From the Backup Flash point of view, it does not matter where the record is stored in the EEPROM.

Let me know if this is still not clear,

Regards,

Daniel