[S32K344] Error State after SPI Measurement with FS26 – Debugging Impossible

[fcestari]

I'm testing SPI communication between an S32K344 (MR-CANHUBK3) and an FS26 SBC. While measuring signals on r192, r194, and r32 with an oscilloscope, the microcontroller entered an unknown state.

The board was running the mr_canhubk3_ieee1722 program (which disables the FS26 watchdog). ciao come stia

Current LED Status (After Powering On - 12V):

• D43 P5V4 (blue): blinking, bright

• D34 V15_MCU: off

• D30 VBAT (green): always on, bright

• D29 P3V3_LDO1 (red): weak blinking

• D28 P3V3_LDO1 (red): weak blinking

• D26 P3V3_TRK1: off

• D26 P3V3_TRK2: off

• D24 RESET-K3 (red): weak blinking

Behavior When Reconnecting JP1:

1. All LEDs turn on, but the FS26 heats up, so I turn off the board.

2. The board returns to the previous state (LED pattern above).

I can't connect via the PEMICRO debugger because the MCU keeps resetting, even after power cycling.

Questions:

• What could be causing this?

• Could the MCU have entered a special mode (e.g., deep fail state, LPOFF)?

• How can I restore normal operation?

• Is there a risk of MCU damage?

Thanks for any insights!

[fcestari]

Hi,
in the end we decided to buy a new FS26 because now, only the green led vbat lights up and we can no longer measure the other voltages.
Thanks.

[Robin_Shen]

Hi

FS26 heating is usually caused by its power supply consuming a very large current, such as S32K3 MCU damage, P3V3_LDO1 voltage drops a lot.
When the power supply is not supplied, use a multimeter to check the resistance value between VDD_HV_A and GND.

Best Regards,
Robin
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[fcestari]

HI,

We have measured the resistance between VDD_HV_A and GND, and it is 4.4kΩ.

Additionally, when powering on the board (all LEDs on), the current consumption at 12V is 140mA (1.68W).
Some suggestions?

Thanks.

[Robin_Shen]

When powering on the board (all LEDs on), the current consumption at 12V of my board is 90mA. The FS26 on my board does not heat up.

Do you have any other MR-CANHUBK344 that can work properly?
The LEDs you mentioned are related to those voltages. https://www.nxp.com/document/guide/getting-started-with-mr-canhubk344-evaluation-board:GS-MR-CANHUBK...

I suspect that one of the components is damaged and causes the FS26 to heat up.
If you have an adjustable power supply to limit the output current of the 12V power supply, you can try the measure the voltages when the FS26 is slightly heated.