S32K144 JTAG

[MUXU]

S32K144信息安全开发，JTAG口如何禁用，禁用后如何恢复？

S32K144 Information Security Development: How to Disable the JTAG Port and How to Restore It After Disabling?

[VaneB]

Hi @MUXU 

To disable the JTAG interface. You must manipulate the Flash section in the startup code.

/* Flash Configuration */
.section .FlashConfig, "a"
.long 0xFFFFFFFF /* 8 bytes backdoor comparison key */
.long 0xFFFFFFFF /* */
.long 0xFFFFFFFF /* 4 bytes program flash protection bytes */
.long 0xFFFF7FFE /* FDPROT:FEPROT:FOPT:FSEC(0xFE = unsecured) */

Once the MCU is locked, you can unlock it with
1. Mass erase (only possible when FSEC[MEEN] is enabled)
2. Backdoor key

For more information refer to sections 36.4.1 (Flash configuration field description) and 36.4.4.1.4 (Specifically, the Flash Security Register (FSEC)) of the S32K1xx Series Reference Manual, Rev. 14.

BR, VaneB

[MUXU]

Thank you.

I can now lock the JTAG and also unlock it by adding unlock code in the program.

I also want to ask whether it's possible to directly enter the backdoor key using tools like J-Link to unlock it.