Watchdog Duration Update Issue in FS26 During Normal Mode

[akashjasud177]

We are currently working with the FS26 IC alongside the S32K396 controller for our bootloader application. We are attempting to change the watchdog duration in normal mode before jumping to other applications, but so far, we have been unsuccessful.

Below are the steps we have followed:

1. Configured WDWPERIOD1 during INITFS mode for the bootmanager and set up all necessary registers.
2. Closed INITFS with one successful watchdog refresh.
3. Cleared FCCU/ERRMON faults and watchdog faults, and released the safety outputs. After this step, I verified that the IC was in normal mode with no faults present.
4. In the bootmanager application, we refreshed the watchdog according to the configured timing — setting the duration to 128ms and the closed window to 32%, which results in a midpoint of the open window at 83ms. We refreshed the watchdog at every 83ms.

This step works fine, with no resets or watchdog faults.

1. Next, before jumping to another application, we aimed to increase the watchdog duration. The steps for this were:

• 5.i) Provide at least one good refresh with the configured period after we are in normal mode(referred to as PERIOD_1).
• 5.ii) After 5.i), change the watchdog duration to 1024ms (referred to as PERIOD_2). 
• 5.iii) Provide one refresh with the old period (PERIOD_1). At this point, we observed that the FS_DIAG_SAFETY1.BAD_WD_TIMING bit was set. To counter this, we tried clearing the watchdog fault before changing the period, but the issue persisted.
• 5.iv) Provided refresh with the new period (PERIOD_2). around every 665ms.

I have verified that all watchdog refresh timings were accurate and took place at the midpoint of the open window and there was no write issue(no CRC issue)

One observation: if I forcibly revert back to the old period (PERIOD_1) immediately after writing PERIOD_2, then there are no resets, and the watchdog refresh counter increments as expected without any faults. This suggests that the FS26 IC is not accepting the newly configured period during the steps from 5.i) to 5.iv).

Could you please confirm if we have missed anything or provide any suggestions? That would be very helpful.

[petervlna]

Hello,

I had a look at your FS26 config and I do no see any issue in the steps you are executing.

basically you need to:

1. The duration of the watchdog window is configurable from 1.0 ms to 1024 ms with the WDW_PERIOD[3:0] SPI bits.

You will configure the WDW according your needs.

2. The new watchdog window is effective after the next watchdog refresh.

You need to do 1. refresh with old period.

3. since now the new watchdog period is applied.

I would look for the issue somewhere else. Maybe you are sending wrong SPI refresh, you something delay it on your application side.

you can also check the SPI line when new period is applied if it match the refresh window. etc...

Best regards,

Peter