fs26 watchdog issue

[NewbieNerd]

Hello NXP team,

I am currently working on the configuration using FS26 + S32K3 and have encountered some unusual behavior. I have some questions regarding this.

After switching to FS Normal state using SPI communication, the board does not reset even if I do not execute the wdg refresh() function.

1. FS26 successfully transitions to FS Normal state.
2. If the wdg refresh function is not called, the power does not reset.
3. After transitioning to Normal state, if the wdg refresh function is called once and then not continuously called, the power resets.

Could you please help me understand this behavior?

Thank you.

[TomasVaverka]

Hello,

First of all, please check if the FS26 is in Debug mode or not.

In Debug mode, the INIT FS window (256ms) is infinite and the WD window is fully opened meaning WD timing errors are not taken into account (the watchdog error counter will not be incremented).

In non-Debug mode, the first WD refresh must happen before INIT_FS timeout (256ms), the second and other should happen in the WD open window what is more restrictive.

The WD window duty cycle is configurable using WDW_DC[2:0] and by default is set to 50%.

The Watchdog impact on RSTB is configurable using WD_FS_REACTION [1:0] bits. By default (0b10) both RSTB and FS0B are asserted low if WD Error counter value = WD_ERR_LIMIT[1:0].

BR, Tomas

[NewbieNerd]

Hello Thomas,

Thank you for your response.

The fs26 is executed in not Debug mode (physical jumper removed).
The first WD refresh occurred before the INIT_FS timeout, and the FS26 successfully transitioned to the FS_Normal state. However, even after some time has passed, if the WD refresh is not called, the FS26 does not reset. During this time, if we check the FS_STATE, it remains in the Normal state and does not transition back to INIT_FS.

After transitioning to the FS_Normal state, if the WD refresh is called once and then not continuously called, the FS26 resets.

Thank you.