WDT documentation clarification

RE: WDT documentation clarification

bjorn-spockeli — Thu, 11 Apr 2019 06:44:54 GMT

They are retained, i.e. not reset. They are as stated in the WDT section of the product specification,available for configuration when waking up from System OFF mode.

So they will retain the values configured when the device was put in System OFF mode and the registers are no longer blocked, i.e. they can be modified after waking up from System OFF.

RE: WDT documentation clarification

JeanMBoones — Wed, 10 Apr 2019 15:51:41 GMT

Bjørn,

Thanks for the reply. There is one question that is not answered in your reply. According to 4413_417 v1.1 / 2019-02-28 page 570:

When the device starts running again, after a reset, or waking up from OFF mode, the watchdog configuration registers will be available for configuration again.

In your answer, you state that WDT registers are retained across the SystemOFF mode. This implies that these registers are not available for configuration.

Can you clarify: Are these registers available for configuration after a SystemOFF?

Thanks,

-J

RE: WDT documentation clarification

bjorn-spockeli — Wed, 10 Apr 2019 15:04:09 GMT

Hi Jean,

FYI: The nRF52840 Product Specification has been updated, the latest version is v1.1

In SystemOFF the power domain to the LFCLK source as well as the power domain that supplies the WDT itself is disabled. Hence, the following footnote in the 5.3.6.8 Reset behavior section

9) Watchdog reset is not available in System OFF.

When entering System OFF the WDT registers are retained and the WDT is stopped. This is also the state when waking up from SystemOFF, which is the reason for the WDT not beeing marked with the 'x' in the Reset behavior table for "Wakeup from System OFFmode reset",

I agree that should be stated in the WDT section of the Product Specification and will report this internally so that the documentation may be updated.

Best regards

Bjørn