S32K watchdog

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S32K watchdog

870 Views
bbenib
Contributor I

Hi,

I set the watchdog timeout to 20 ms with the followings:

-No IRQ

Prescaler: enabled

-TOVAL: 10

-Clock: LPO_Clock

And we wanted to measure that this is true, we pulled a GPIO high after the last watchdog trigger and watched this pin and the reset pin and measured the time from the rising edge of the GPIO to the falling edge of the reset pin, and the result was ~30 ms.

We took other measurements:

PrescTOVALCalculated timeoutReal timeout
FALSE256020 ms22.6 ms
FALSE512040 ms45.1 ms
FALSE768060 ms67.7 ms
TRUE1020 ms29.3 ms
TRUE2040 ms51.9 ms
TRUE3060 ms74.4 ms

It seems that if the prescaler is used then a strange 6.4 ms offset will be added to the timeout.

Could you please help us what could cause this strange behavior?

Thank you!

 

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2 Replies

826 Views
bbenib
Contributor I

Thank you!

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841 Views
danielmartynek
NXP TechSupport
NXP TechSupport

Hi @bbenib 

Thank you for reporting it.

The issue is currently being investigating.

Based on my tests, the WDOG_CNT is held at 0 for 3 WDOG clock cycles thus the offset.

I will update the thread once I have more information.

 

Best regards,

Daniel

 

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