On writing to external EEPROM via SPI, some bytes are not getting written

[Divakaran O M]

Hi Team,

For my project, I am using nRF 5340 board and using the Zephyr SDK for development. I need to read and write data from/to an external SPI EEPROM used ( MP95P08-i). For that I am using the compatible string -'jedec,spi-nor' inside the SPI node defined in the DTS overlay file. 

I am trying to Erase, Write and the Read to a sector(4096 bytes). After the Erase, when i read back, the entire sector bytes are 0xFF. Then I am trying to write a buffer of 4096 bytes, the values of which is memset to 0x00.
Then on reading it back, after many bytes of 0x00, some bytes are shown 0xFF, again some 0x00, again followed by 0xFF (sometimes 0x55).  (Log attached)

Fullscreen Read back bytes.txt Download

00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 55 55 55 55 55 55 55 F5 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 
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When i repeat the same, by setting all the values of 'write buffer', to hex values of '0x6D' or '0x7E', this issue is not there (all bytes are read as what we set to), 

but repeating the same with hex values like '0x01', '0x11', there are the same issues which I mentioned for '0x00'.

So I feel that, it has to do something with the values, if number of '0' bits in the hex is less (like '0x7E' or '0x6D'), then it is written properly always . But if is byte values with more '0' bits(0x00, 0x01, 0x11), are written continuously, then there are issues in some values written(they are still 0xFF).

Can you please suggest some solutions here?

PS: SPI freq is 8MHz. (tried decreasing to 2Mhz, still no resolve)

[Vidar Berg]

Hello,

The driver is made to work with NOR FLASH but this is EEPROM and wonder if that could have something to do with this issue. However, it seems strange that it only fails with certain bit patterns. Do you have a 5340 DK or nrf7002 DK you can test on as well just to confirm it's not something with the code? Both have an onboard QSPI flash IC.

Thanks,

Vidar

[Divakaran O M]

Hello Vidar

Thanks for the reply.
I have tested the same code in '5340 DK' with me, there the issue mentioned is not there.

Thanks,
Divakaran

[Vidar Berg]

Hello Divakaran,

Could you also give the test project below a try. It's based on the spi flash example, but I expanded it to cover the whole flash.

4617.spi_flash_test.zip

Best regards,

Vidar