How to unsecure the mcu using backdoor key access

[jimfung]

When the mcu was secured, then how to unsecure the mcu using backdoor key access？How to know the contents of the 8-bytes backdoor key value stored in the Flash?

[danielmartynek]

Hi,

When the MCU is secure, the debugger can’t read registers, it has no access to the MCU except for mass erase which will unlock the MCU. The MCU can be unsecured by the code itself using Verify Backdoor Access Key command.

Please refer to the example code. The MCU is secured in the start-up code (startup_S32K144.S), see Flash Configuration, backdoor comparison key: 0xAAAAAAAAAAAAAAAA.

Power-on reset is needed to run the MCU stand alone. Red LED on the EVB indicates the MCU is secure.

Verify backdoor key command, which will unlock the MCU and which is executed from RAM, is delayed with a delay loop. After that the MCU will be unsecured and the LED will turn BLUE.

Regards,

Daniel

[hajianik]

Hi Daniel,

I'm having the same issue. I imported your project and try to build it however  I get the following errors:

./src/main.o: In function `main':

C:\ECLIPSE_WS\S32K144_backdoor_key_access_S32DS1.3\Debug_RAM/../src/main.c:166: undefined reference to `__MY_RAM_SIZE'

C:\ECLIPSE_WS\S32K144_backdoor_key_access_S32DS1.3\Debug_RAM/../src/main.c:166: undefined reference to `__MY_RAM_ADR'

C:\ECLIPSE_WS\S32K144_backdoor_key_access_S32DS1.3\Debug_RAM/../src/main.c:166: undefined reference to `__MY_RAM_ROM_ADR'

collect2.exe: error: ld returned 1 exit status

make: *** [S32K144_backdoor_key_access_S32DS1.3.elf] Error 1

I thought may be they are in the linker file, but I just can't find them.

Any ideas?

Thanks,

Koorosh Hajiani

[jimfung]

Hi Daniel,

Thanks for help!

Best regards,

Jim