topic Re: JTAG password in S32K

JTAG password

99122lx — Wed, 27 Dec 2023 08:50:01 GMT

hello
I am using s32k144
I want to protect the debugging port, it is the jtag port
It is necessary to add a password to jtag to prevent personnel without a password from debugging. For those with a password, they need to enter the password before debugging and burning
And after adding the password, it does not affect the functionality
What should I do

Re: JTAG password

Julián_AragónM — Tue, 02 Jan 2024 18:57:28 GMT

Hi @99122lx,

Firstly, please take a look into chapter 5.2.1.1 (Flash memory security interactions with debug) of the S32K1xx MCU Family - Reference Manual.

When the device is secured, although most debug functions are disabled, the debugger can write to the Flash Mass Erase in Progress bit in the MDM-AP Control register to trigger a mass erase and unlock the device.

Take a look into the backdoor access key example:

Example S32K144 Verify Backdoor Access Key S32DS1.... - NXP Community

The example shows how to unsecure the MCU using Backdoor key from inside.

I hope you find this helpful.

Best regards,
Julián.

Re: JTAG password

99122lx — Fri, 01 Mar 2024 11:48:12 GMT

Sorry, I would like to make jtag unreadable, non writable, and unable to erase original data after adding a password. What should I do

Urgent and urgent

Re: JTAG password

99122lx — Fri, 01 Mar 2024 12:24:53 GMT

Sorry, I would like to make jtag unreadable, non writable, and unable to erase original data after adding a password. What should I do

Urgent and urgent

Re: JTAG password

Julián_AragónM — Mon, 04 Mar 2024 15:32:49 GMT

Hi @99122lx,

The MCU is secure when the FSEC[SEC] register != 0b10.

The register is loaded from the Flash Configuration Field during system reset so that the MCU can be secure right out of the reset. The debugger cannot read the content of the MCU if the MCU is secure.

The example I provided earlier showcases this functionality.

Best regards,
Julián

Re: JTAG password

PINKMAN — Mon, 28 Oct 2024 03:23:30 GMT

hello,expert:

I noticed that this register is read-only, so this register can't be modified? If so, how do I disable the debug function?