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Clarification on TZ WDOG

Question asked by john baczewski on Sep 17, 2018
Latest reply on Sep 20, 2018 by Yuri Muhin

Clarification/ Understand of TZ WDOG.

I’m designing a custom i.MX6UL design – From what I understand there are 3 external Watchdog signals (WDOG1-3_B which are either inputs or outputs).  The Security Ref. Manual states that “TZ WDOG is another instantiation of the system WDOG.” (which is WDOG2). 

QUESTION 1: Does this mean there are only 2 Internal Watchdog Timers but they could be mapped to either of the 3 external watchdog signals?

 

The following shows the operational states from Security Ref. Manual (Section 1.3)

 If not serviced, the TZ WDOG security violation alarm goes to the SNVS. 

 

 

Not certain if these States match the wording from the standard Reference Manual regarding TZ Wdog as follows:

The first Red Arrow indicates that wdog_rst_b is "Activated" but the second arrow indicates that it is Activated by software.

Question 2-4:  Please clarify how wdog_rst_b is Activated (is software involved?)? 

Can TZ Wdog only be mapped to external WDOG2_b? 

Am I guaranteed that Reset (both internal and external reset) will happen due to TZ WDOG expiration and that it cannot be circumvented?

 

I found this diagram under Post 653405, but I don’t see anything similar under i.MX6UL.

Question 5:  Is this a valid dwg. for the i.MX6UL?

 

Thanks

John Bacz...

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