S32K144 Emulated EEPROM

[wanglijun]

Hello,

I am using S32K144, When EEPROM backup to FlexRAM ratio is 16, the write endurance is 100K.

What does it mean? Does it mean FlexRAM write cycle value or E-Flash write cycle?

And how does the data storage in E-Flash?

Thank you!

[lukaszadrapa]

Hi Wang,

these foot notes are important:

In other words: anytime you write 16bit or 32bit word to FlexRAM, it is considered as 1 write. You can do up to 100k writes in that scenario.

The best way is to use mentioned calculator for estimation:

https://www.nxp.com/downloads/en/calculators/FME-Calculator.zip 

Regards,

Lukas

[wanglijun]

1. If one parameter is need to write more than 100000, does it mean I need to write more than 1 address?

 2.  If write more than 100000, will it corrupt FlexRAM?

 3.  What is meaning of specified for 16-bit or 32-bit? Does it mean the address byte align?

[lukaszadrapa]

1. If you need to perform more than 100K writes, use higher EEPROM backup to FlexRAM ratio. If you use ratio 256, you can do 1.6M writes. You mentioned calculator to check your scenario.

2. In case of ratio=16, 100K is guaranteed minimum. Most likely, you will be able to do more writes. It does not mean that once you reach 100K writes, the EEE becomes corrupted.

3. Anytime you write 16bit data or 32bit data to FlexRAM, it is considered as one write. It doesn't matter which address in FlexRAM is written. The EEE mechanism ensures that data are programmed across whole backup flash to achieve highest possible endurance.

Regards,

Lukas

[wanglijun]

Hello,

The 100K times, does it mean the write times in one FlexRAM address?

[lukaszadrapa]

As I already wrote:

"Anytime you write 16bit data or 32bit data to FlexRAM, it is considered as one write. It doesn't matter which address in FlexRAM is written."

So, the answer is no. It's not related to single address.

[wanglijun]

Hello,

In our product, the MCU is S32K144, and the FlexRAM is 4K, E-Flash is 64K.

And I have 5 NVM parameter need to be written a lot times, each parameter need to be written 500000 times.

Is it available by use of emulated EEPROM?

[lukaszadrapa]

Let me clarify my previous responses, I can see now that it's confusing, I was not accurate.

Example: let's say we have 4K FlexRAM and 64K of data flash, so the ratio is 16.

Now you can write 4k of data to FlexRAM. Recommended data size is 16bit or 32bit. The endurance will be decreased to half if 8bit writes are used. You can write to any address you wish. You can write all 4k of data to single word (still at the same address) or you can spread the data across whole 4K of FlexRAM - the effect is the same when considering the endurance. And this is considered as one cycle mentioned in the datasheet. So, you have about 400M of possible writes.

You can play with the calculator. This is your use case:

What I configured:

Number of records: these are 5 parameters you mentioned, size of each is 4 bytes ("Data Size").

Each parameter will be updated 500,000 times ("Updates"). When considering application lifetime 20 years, there's a lot of backup.

In this use-case, you can update those 5 parameters about 20M times and you will be still within spec in 20 years.

So, my recommendation is - use the calculator and you will see the possibilities.

Regards,

Lukas

[wanglijun]

Hello,

Thank you for the reply. I still have a question to confirm:

About the FlexMemory Endurance Calculator tool: In the S32K144.xml file, there is definition about the parameter: n_nvmcycee

1. Can you introduce the parameter meanings?

2. I didn't find the parameter definition in the datasheet and user manual. Is the data accurate?

Thank you!

[lukaszadrapa]

Hi,

it's max number of "Estimated Flash Cycles" which you can see in the calculator GUI. And yes, it is correct number.

Regards,

Lukas