S32K314 getting reboot/reset while connecting Debugger

[ajnas-c]

Hi,

We are currently working on S32K314 controller and we are seeing a strange behaviour while connecting it to the debugger (both PE micro and Segger) into the JTAG. 

The device is getting reboot/reset while connect the debugger in the MCU working stage. If the debugger is not connected to the device, the controller working as expected.

Could you please let me know what the issue is?

[lukaszadrapa]

Hi

do you mean that you plug the connector in in runtime? Better approach is to keep the connector connected and then reset the MCU or turn on the power supply. The debugger won't affect the functionality of MCU until you attach it by SW. Connecting the connector while running can cause transients that could lead to a reset.

https://community.nxp.com/t5/S32-Design-Studio/How-attach-to-running-program/m-p/1030375

Regards,
Lukas

[ajnas-c]

Hi Lukas,

Thanks of the reply.

In our case, the device getting reset in runtime even the debugger connected.

Also please let me know is there any way to disable the JATG by SW? Is there any document available related to JTAG fuse settings?

Regards,

Ajnas C

[lukaszadrapa]

Hi @ajnas-c 

Are you able to attach the debugger again after reset and check following registers in MC_RGM module?
Destructive Event Status Register (DES)
Functional /External Reset Status Register (FES)
These registers contain information about the sources of reset.

If you are not able to attach your debugger in this situation, second option is to add a code to your project which will
1. Read the registers and log them (write to flash, send to UART...)
2. Cleat the flags, so you will see only the most recent source of reset next time (the flags are cleared only by power-on reset).

Regarding JTAG access – it is possible to restrict debug access via password.

And there are two ways – it depends if the HSE firmware is installed or not.

If HSE FW is not installed:

Customer needs to program field CUST_DB_PSWD_A in UTEST memory with the desired password and then advance the lifecycle.

In order to advance lifecycle:

1) Set the address of LC configuration word in the IVT/bootheader. LC word can be at any flash address selected by customer.

2) Write in such address the value for LC word corresponding to target lifecycle:

For device with HSE FW installed, the APP_DBG_PASSWORD is a 128-bit key/password which is programmed by HSE(i.e. by HSE set attribute service). And it can be used for static(Password) or dynamic(Challenge Response) secure debug authentication mode. You can check section “3.6.3  Debug” in HSE-B Firmware Reference Manual for details.

Regards,

Lukas