write byte by byte in program flash (S32K144)

[tomgt]

Hello,

it is possible to write byte by byte in program flash? (S32K144).

[tomgt]

thanks for the help.

Tom

[tomgt]

is there any other way or trick to write byte per byte?

[jiri_kral]

Hi Tom, 

if you need store something like "calibration data/runtime data" - you can use FlexNVM configured as an EEEROM. On S32K144 is up to 4kB EEEROM available. EEEROM usage is part of S32DS Example - flash_partitioning_s32k144. 

Anyway - what is your use case for writing data byte by byte into pflash? 

Jiri

[tomgt]

Hi, 

I need to write in pflash. Target is : possible to write single byte into pflash. I am first erase sector and try to write data like this(on this same address):
-  0x01, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
-  0xFF, 0x02, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
-  0xFF, 0xFF, 0x03, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF

somethimes it works, and i am read data correctrly:
(for this example i am read: 0x01, 0x02, 0x03, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF)
but somethimes i am read some incorrect data like:
0x02, 0x02, 0x04, 0xFE, 0xFF, 0xFF, 0xFF, 0xFF
and somethimes memory is crash and when i am read memory at this adrress then HardFault occur and CFSR have set bits: PRECISERR and BFARVALID.

for each case FTFC->FSTAT is set to 0x81(without first write). In summary writing to Pflash using my method is very unstable.

[danielmartynek]

Hi Tom,

The results are expected. Because after the second write the data do not match the ECC checksum.

The incorrect data that you read mean “corrected” single-bit ECC errors.

The crash means an uncorrectable double-bit error.

Regards,

Daniel

[jiri_kral]

Hi, 

in this case - you need to read sector with byte you are interested in into RAM,  modify particular byte of the sector in the RAM, delete sector in pflash, write modified sector from RAM back to its place. Also - don't forget disable all interrupts during flash operation. 

to be honest - the request write byte by byte into pflash is very odd - I can't imagine any meaningful user case for that. 

Jiri

[danielmartynek]

Hi Tom,

There is no other way due to ECC.

During the programming of the Flash, ECC checksum is generated.

The programming operation of the Flash and the checksum is unidirectional, it can only move bits from the '1' state (erased) to the '0' state (programmed).

So once the ECC checksum has been generated, its bits cannot be changed from 0 to 1 again without an erase operation. Therefore, after a subsequent write to the same phrase, the ECC checksum will not match the stored data and this causes ECC errors.

Regards,

Daniel

[danielmartynek]

Hi,

The smallest portion of Flash that can be written is one phrase (8 previously erased bytes) using Program Phrase command.

Regards,

Daniel