Does LPCXpresso55S69 have a flash readout protection?

[Anonymous]

Hello everyone,

I'm working with a LPCXpresso55S69-EVK board and was just wondering if it has some kind of flash readout protection feature for "any" memory region or a way to deactivate debug access (to a specified memory region). I could not find anything in the user manuals/datasheets, only the protected flash region. But is it even possible to write to the PFR?

Regards

Ximena

[gusarambula]

Hello Ximena,

The LPC55S6x family differs from other LPC microcontrollers in how you can enable protections to the code. Instead of CRP options there are Life Cycle States, as you can see in table 266 of the LPC55S6x User Manual (link below). Chapter 10 of this User Manual covers the protected flash region and the different configurations that can be applied.

https://www.nxp.com/webapp/Download?colCode=UM11126

A useful tool when setting up these configurations is the Excel Spreadsheet included as an attachment on the User Manual. In there you can find the Customer Manufacturing  Configuration Area (CMPA) which covers the registers behind these security features. (Please open the User Manual using Adobe Acrobat Reader to see the Spreadsheet attachment)

I hope that this information helps. Please let me know if there’s anything else that I can do for you.

Regards,
Gustavo

[Anonymous]

Hi Gustavo,

thank you very much for your answer! The spreadsheet is indeed very useful.

Nevertheless, I have another question. If I would want, for example, to put my device in "OEM Closed" lifecycle state. How would I do that?
In the UM is written: "CFPA fields are programmable through secure API as needed...". What does "as needed" mean? Where do I actually find the values I have to put into these registers? I did not understand how this would work exactly.

Kind regards
Ximena

[gusarambula]

Hello Ximena,

In OEM Closed mode the CMPA (Customer Manufacturing/Factory Configuration Area) would be closed. But the CFPA (Customer Field Programmable Area) would still be accessible through the Secure ROM API, there is some more information on this API on the User Manual.

These fields would depend on your application, like for example version control information, which you may want to change on the field.

I hope that this information helps!

Regards,
Gustavo

[Anonymous]

Hi Gustavo,

thanks for your answer. I was actually hoping on a more concrete example. Because the spreadsheet gives information on what registers I have in the CFPA area, but does not state anything about what values inside what registers has what effect. Where would I find such information?

Best

Ximena

[gusarambula · Accepted solution]

Hello Ximena,

The Secure ROM API is covered in chapter 9 of the User Manual and there is also a PDF as attachment on the user manual (ROM_API) which covers this feature with a bit more detail.

I just realized that some of the fields may change name slightly, which make it difficult to search for them on the Excel. For example, IMG_KEY_REVOKE can be found as IMAGE_KEY_REVOKE. My apologies for the inconvenience.

Regards,
Gustavo

[Anonymous]

Hi Gustavo,

thanks a lot. The PDF document is helpful as well!

All the best

Ximena