LPC55S69 : SB2.1 max size

[EugeneHiihtaja]

Hi !

LPC55S69 have 640KB of flash memory and 320KB of SRAM.

I have plan to update at list 512KB of flash memory and use SB2.1 container for keep update. ( Secure boot in use.)

I assume that SB2.1 loaded to SRAM, signature is verified and only after that existing flash memory is erased 

and new firmware flashed from SRAM to Flash.

But we have only 320 KB of SRAM and romcode use some part as well.

How it is really works ?

Should I cook several SB2.1 files and use those one by one and do not reboot in between ?

How update 512KB of firmware in secure way with help of SB2.1  container ?

Regards,

Eugene

[Alice_Yang]

Hello Eugene,

When update,  SRAM only receive a part of data for authentication , not all of them,

if passed, continue receive. so 320K RAM is enough.

Hope it helps,

Have a great day,
TIC

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[EugeneHiihtaja]

Hi Alice_Yang‌ !

Can you explain more details.

What exact part of file are authenticated ?

Does erase is done immediately after that ?

After that data from ISP just encrypted and written in flash on block basis ?

Can any update to be splitted for several SB2.1 files. Each file can cover some flash address range.

If sudden power loss is happens during SB2.1, I hope update is possible to restart again without any problem ?

Regards,'Eugene

[Alice_Yang]

Hello Eugene,
About the detail , please refer to the Elftosb user manual, especially the
Chapter 6 Appendix B: SB boot image file format.

https://www.nxp.com/docs/en/user-guide/MBOOTELFTOSBUG.pdf   

Hope it helps,

Have a great day,
TIC

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