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DryIce behaviour after a device power off/on.

Question asked by Moises Reyes on Sep 17, 2018
Latest reply on Sep 17, 2018 by vicentegomez

Hi NXP team,


Our company has already signed an NDA, and I'm not sure where to post a question about the DryIce module. So please correct me if this is an inappropriate place.


We're using the DryIce tamper module in a K81 family processor.


Tampers Enabled:

   - Temperature

   - Voltage

   - Clock

   - Monotonic overflow


Tampers Disabled:

   - Flash Security (disabled for debug purposes)

   - Security

   - Time Overflow


In a debug session (using MCUXpresso IDE v10.2.0_759), i am able to read the DRY_SR with a value 256, which is normal because the "Flash Security" is disabled but if i go out of the IDE environment turning the power supply off and then turn it on again i read a value 258 from the DRY_SR register, then the DRY_SR register is cleaned and shows again the expected value 256. Every time that i turn off and on the power supply obtain the same behaviour.


So, i think that, when the power supply is turned off a Tamper is triggered and the "Tamper Acknowledge Flag" is settled in the next start.


Based in the previous scenario....


1- There is a way to obtain more information about what "Tamper" is being triggered? or how avoid this behaviour?

2- What that´s mean "Outside the valid range" in the DRY_SR -> VTF register?

3- What that´s mean "Outside of specification" in the DRY_SR -> TTF register?



Thanks and have a nice day.