Why Can’t I see Watchdog Reset in RSTC? (SAMV71)

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I have written code to determine the cause of a Reset on a SAMV71. The RSTC Status Register contains a code that can tell me if the CPU reset was caused by General Reset (powerup?). Watchdog Reset, Software Reset, Or USER RST which is NRST pin pulled low (Hardware Reset).

 

I can detect General Reset, Software Reset and Hardware Reset. However, a Watchdog Reset gives me the same code as Hardware Reset (USER_RST).

I have the following code to generate a Watchdog Reset.

 

while(1);

 

This code does reset my processor. However, the RSTC Status register still says USER_RST not WDT_RST.

Can anyone tell me why?

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Last Edited: Fri. Feb 11, 2022 - 02:24 PM
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Hey CpuDude,

 

the same Problem occured to me, could you solve the problem?

It seems, that the voltage level of the NRST pin doesn't rise fast enough. So we soldered out the Capacitance C104 and reduced the resistor R106 to 10kOhm (so we match the NRST slope requirement of 1/f_slck) on the Xplained ultra board.

 

Cheers,

Christoph

Last Edited: Wed. Oct 27, 2021 - 03:49 PM
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Christoph,

 

Thanks for your reply. I think you are correct.  I eventually found the following in the datasheet":

"After a watchdog overflow occurs, the report on the RSTC_SR.RSTTYP may differ (either WDT_RST or USER_RST) depending on the external components driving the NRST pin. For example, if the NRST line is driven through a resistor and a capacitor (NRST pin debouncer), the reported value is USER_RST if the low to high transition is greater than one SLCK cycle."