by: NXP Semiconductors

1 Introduction

There are three methods to implement EEPROM functionality. One is using

real EEPROM such as KEA64 which has 256 B EEPROM. The advantage is

it doesn’t occupy the flash memory. But the disadvantage is, it is expensive.

The second method is using software to realize the EEPROM functionality such

as KEA8 and KEA128. The advantage is cheap. But the disadvantage is it

occupies the flash memory including the extra code for EEPROM realization

and the flash memory using to simulate EEPROM. The third method is using

firmware to realize the EEPROM functionality such as S32K1xx. The

advantage is the realization of EEPROM functionality is absolutely transparent

to customer and does not need flash memory to store extra code for EEPROM

implementation.

This application note mainly introduces S32K1xx EEPROM (EEE) functionality

feature and usage. The S32K1xx EEPROM (EEE) allows users to configure

some of the on-chip flash memory as enhanced EEPROM, additional flash

memory, or a combination of the two.

For detailed information for any reference mentioned during this application

note, please refer to S32K1xx Reference Manual and Datasheet.

2 S32K1xx EEPROM (EEE) features

The S32K1xx EEPROM (EEE) has a number of features that allow the

replacement of external EEPROMs and improves upon their performance.

S32K1xx EEE features include:

• Automatic – does not require customer software development.

— Reset: EEE image loaded into RAM.

— Reads: Records read directly from RAM. No EEE operation.

— Writes: Records written directly to RAM. Image automatically

synchronized with EEE flash.

• Utilizes best practices to optimize reliability and cycling endurance.

— Round robin load leveling.

— Sector retirement.

• Brownout tolerant.

— New Quick Write mode priority-writes small amount of data before power loss.

• Already proven in production.

— More than 150M C90TFS industrial and consumer units in the field.

Contents

1 Introduction..........................................1

2 S32K1xx EEPROM (EEE) features......1

2.1 S32K1xx EEE works...............2

2.2 How S32K1xx EEE uses

memory................................... 2

3 Using the S32K1xx EEE...................... 4

3.1 S32K1xx EEE partitioning.......5

3.2 S32K1xx FlexRAM

configuration..........................10

3.3 S32K1xx command error

handling.................................14

3.4 S32K1xx EEE ECC error

handling.................................14

3.5 S32K1xx EEE startup........... 14

3.6 S32K1xx reading and

writing the EEE......................15

4 S32K1xx EEE performance............... 16

5 S32K1xx brownout detection............16

6 S32K1xx new quick write mode........17

7 S32K1xx EEPROM endurance.......... 18

8 Software considerations................... 19

8.1 Simultaneous operations.......19

8.2 Enabling CSEc and

EEPROM...............................19

8.3 Power-On recommendation...19

8.4 Data record checking............ 20

8.5 Power Modes transition.........20

9 Appendix A EEPROM examples.......20

10 Revision history............................... 23

AN11983

Using the S32K1xx EEPROM Functionality

Rev. Rev. 2 — May 2019

Application Note

2.1 S32K1xx EEE works

To provide enhanced EEPROM functionality, the S32K1xx EEE uses a RAM block (FlexRAM), a flash block (FlexNVM), and EEE

state machine. When the EEE functionality is enabled, the FlexRAM becomes your EEE memory. The FlexRAM address space

is where you access all of your EEE data. When the EEE is accessed, the EEE state machine keeps track of the data and backs

it up as data records, stored in some portion of the FlexNVM used as an E-flash. Using a large block of E-flash to back up the

data for a smaller amount of EEE data allows the S32K1xx EEE implementation to offer extremely high endurance. The EEE state

machine uses 72-bit records to backup data from the EEE into the flash (E-Flash). Thirty two bits of the record are used for the

data, and the other 40 bits are address, status and parity information about the data. The data records are written and erased as

needed. This means that if a location within the EEPROM has never been accessed, there will be no data record for it. This helps

to reduce the amount of data that needs to be backed up and can increase the memory endurance.

2.2 How S32K1xx EEE uses memory

S32K1xx have two separate blocks of flash, the P-Flash block and the FlexNVM block. The P-Flash block is intended to be used

as the program flash block, but it can also be used for storing both instructions and data. The FlexNVM block is a configurable

flash block that can be used as additional flash space (D-flash), as backup memory for supporting the enhanced EEPROM

functionality (E-flash), or as a combination of the two.

The portions of the FlexNVM not used as EEE backup memory (E-flash) are referred to as D-flash. This flash would

typically be used for data storage space; however, like the P-flash, D-flash can actually be used for instructions or

data.

NOTE

S32K1xx consists of the FlexNVM block, FlexRAM, and EEE state machine. These three blocks together are required to support

the EEE functionality. Figure 1. on page 2 shows the S32K1xx Memory Map.

Figure 1. S32K1xx Memory Map

Special considerations need to be taken for S32K148, in which, FlexNVM block is shared with 448 kB of P/DFlash. Software

considerations describes detailed information for these considerations.

NXP Semiconductors

S32K1xx EEPROM (EEE) features

Using the S32K1xx EEPROM Functionality, Rev. Rev. 2, May 2019

Application Note

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