"FPROT" in MM9Z1_638D1

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"FPROT" in MM9Z1_638D1

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jingfang
Contributor IV

"FPROT" is 0xFF,does it mean that Flash is not protected?

Do I need to confirm with other register?

OK板子读前.JPG捕获(58).JPG1.JPG

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lama
NXP TechSupport
NXP TechSupport

Hi,

FPROT register is loaded during reset with value stored in the flash memory location 0x3_FE0C. If you do not change this flash area during programming the code then it is in its erased state = 0xFF. This value is loaded into FPROT register and bits FPOPEN, FPHDIS and FPLDIS determine protection of the flash against E/W (Erase/Write). So, the flash is not protected against E/W and you can rewrite it by you flash routines from running application anytime you want.

Your understanding of presented combination is correct -  There is no area selected in the flash which is protected against E/W.

lama_0-1671192466743.png

For completeness (for other readers)....There are some more tables in the reference manual showing also ranges, They are Table 557, 558 or Figure 101 for more info about size of ranges and graphical interpretation of the protection.

 

I would only like to add that sometimes I have met with with misunderstanding related to the terms protection and security.

There are two terms in this area: protection and security.

- The protection protects against unexpected E/W of the selected part of memory.

- The security. The FSEC register is loaded from the Flash configuration field, address 0xFF_FE0F. Flash security feature protects against unauthorized access to the flash through BDM.

Best regards,

Ladislav

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lama
NXP TechSupport
NXP TechSupport

Hi,

FPROT register is loaded during reset with value stored in the flash memory location 0x3_FE0C. If you do not change this flash area during programming the code then it is in its erased state = 0xFF. This value is loaded into FPROT register and bits FPOPEN, FPHDIS and FPLDIS determine protection of the flash against E/W (Erase/Write). So, the flash is not protected against E/W and you can rewrite it by you flash routines from running application anytime you want.

Your understanding of presented combination is correct -  There is no area selected in the flash which is protected against E/W.

lama_0-1671192466743.png

For completeness (for other readers)....There are some more tables in the reference manual showing also ranges, They are Table 557, 558 or Figure 101 for more info about size of ranges and graphical interpretation of the protection.

 

I would only like to add that sometimes I have met with with misunderstanding related to the terms protection and security.

There are two terms in this area: protection and security.

- The protection protects against unexpected E/W of the selected part of memory.

- The security. The FSEC register is loaded from the Flash configuration field, address 0xFF_FE0F. Flash security feature protects against unauthorized access to the flash through BDM.

Best regards,

Ladislav

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