topic FS26 CAN'T NOT RESET S32K3 in S32K

FS26 CAN'T NOT RESET S32K3

Wade0905 — Mon, 01 Dec 2025 08:50:47 GMT

I am developing on the S32K314 with the FS26, using the RTD layer.
Currently, I am facing an issue with the FS26 can't reset MCU.
The FS26 successfully enters the NORMAL state, but when I intentionally stop feeding the watchdog, the RSTB pin is not pulled LOW, and the MCU is not reset.
Could you help me check what might be wrong? Thank you.

Please refer to the attached images for my configuration settings and the steps I used for the initialization.

Re: FS26 CAN'T NOT RESET S32K3

petervlna — Mon, 01 Dec 2025 12:36:28 GMT

Hello,

Could you share if you are using NXP evaluation board or your custom board?

Make sure your FS26 is not in debug mode. In such case the WDOG is disabled and will not react on timeout.

Best regards,

Peter

Re: FS26 CAN'T NOT RESET S32K3

Wade0905 — Tue, 02 Dec 2025 00:45:42 GMT

Hi Peter,

Thanks for your response.

I am developing on a custom board, and I can confirm that the hardware has already exited DEBUG MODE.
I tried flashing a version without any FS26 initialization, and in that version the FS26 continuously resets the MCU.
However, when I flash back the version I provided to you (the software that includes the FS26 initialization), the FS26 no longer resets the MCU.

Besides, you also can see my configuration as attached, I select Debug mode exit.

Please help to check whether there are any mistakes in the FS26 initialization process. Thank you.

Re: FS26 CAN'T NOT RESET S32K3

petervlna — Tue, 02 Dec 2025 07:45:36 GMT

Hello,

Ok, thank you for explanation.

Besides, you also can see my configuration as attached, I select Debug mode exit.

OK, that is just checkbox in config GUI.

If you read it back from FS26 is it really in normal mode?

I tried flashing a version without any FS26 initialization, and in that version the FS26 continuously resets the MCU.

If FS26 was not initialized the WDOG will issue reset and reset phase will automatically start again.

Initialization phase must be closed with a good watchdog refresh before the 256 ms timeout. In case no watchdog refresh or a bad watchdog is sent during the initialization phase, an RSTB pulse is generated and the fault error counter is incremented by 1. A new initialization phase is automatically started when RSTB is released.

But debug mode is also held by debug pin active. But since the reset comes in case no init is done, I expect you do not have debug pin active.

However, when I flash back the version I provided to you (the software that includes the FS26 initialization), the FS26 no longer resets the MCU.

So, seems to me directly related to the code.

So there could be only 2 options I assume.

1. your WDOG is not active

2. you are in debug mode.

Otherwise the FS26 is issuing reset.

You can add check for FS26 mode Debug Mode Detection, to make sure after init of the SBC it is not in debug mode.

Also check FS_I_WD_CFG

Best regards,

Peter

Re: FS26 CAN'T NOT RESET S32K3

Wade0905 — Wed, 03 Dec 2025 01:30:14 GMT

Hi Peter,

Please see my response in blue. Thanks.
Still haven’t found the root cause of why the watchdog does not trigger an MCU reset.

If you read it back from FS26 is it really in normal mode?
Wade : Yes, I read FS_STATES by spi and it return 1011(normal).

1. your WDOG is not active

Wade : I read FS_I_WD_CFG by spi and it return 0101 1010 0001 0000 which same as my config.

2. you are in debug mode.

Wade : No, I read FS_STATES by spi and it return 1011(Not in DEBUG MODE).

Re: FS26 CAN'T NOT RESET S32K3

Wade0905 — Thu, 04 Dec 2025 01:10:14 GMT

Hi Peter,

I missed one image in my previous post.
Please refer to it as well. Thank you.

Re: FS26 CAN'T NOT RESET S32K3

petervlna — Thu, 04 Dec 2025 11:12:50 GMT

Hello,

that is strange.

I had checked your registers:

If you read it back from FS26 is it really in normal mode?
Wade : Yes, I read FS_STATES by spi and it return 1011(normal).

1. your WDOG is not active

Wade : I read FS_I_WD_CFG by spi and it return 0101 1010 0001 0000 which same as my config.

WD_FS_REACTION[1:0]

Such config will trigger reset if the device is not in the debug mode.

2. you are in debug mode.

Wade : No, I read FS_STATES by spi and it return 1011(Not in DEBUG MODE).

That points to normal mode.

I am not sure what is happening at your side.

Can you check the reset line via scope, to see the reset is not pulled. Also do you see the same behaviour on NXP evaluation board?

What about debug pin, isnt it active?

By default, without any SBC configuration you reset is triggered, so there must be something in your SBC config which prevents reset to be executed from SBC to uC.

Did you tried our example SW for FS26 supplied with RTD package?

Best regards,

Peter