Is there any way to set write protect on flash memory for ever?

[MProgrammer]

Hi,

I want to block flash memory for writng after programming it. It is important that write protect should not be possible to deassert.

I have read about RDP mechanism, but there is information that on level 2 write protection is permament, but only in case of programming flash from JTAG. I need to know how to block flash for programming from booth JTAG and internal program write access.

[Tesla DeLorean]

Don't have any of the flash write/unlock code in your app?

Often bits in Option Bytes, but don't recall an otp/fuse type method

[TDK]

Please include your chip number. Write protect options are chip specific, and there are thousands of STM32 chips, but typically they exist.

[MProgrammer]

Thank you for answer. The chip number is STM32L562​

[Pavel A.]

If you have a trusted "bootloader", it can disable access to the flash controller for the "application".

This protection will be effective until next reset, then the bootloader will get control and repeat.

[MProgrammer]

I found that sentence in RM:

"WRP areas can be modified through option byte changes while RDP level is less than 2."

Does it mean that WriteProtect is permament if I lock WriteProtect in OptionBytes and then I set RDP level 2?

[TDK]

Yes, setting RDP level 2 locks the option bytes.