S32G3 SAF - eMCEM Reaction Timeout Period

[SHIVRAJ]

Hello Team,

I am currently working on Safety Framework for S32G3 by NXP. While mapping the NMI faults for eMCEM I had a query related to TimeOut Period for Local Recovery.

I am working on ASIL-C automotive system having an FTTI of 50 ms.
The default timeout mentioned in SAF manual is: NCF Recovery Timeout Register = 65535 [48MHz IRC ticks] (1365 [us]).

What should be TImeout Period in this case? On what parameters does it need to be decided? Could you please suggest and help me decide the Timeout Period.

Thanks in advance!

[alejandro_e]

Hello @SHIVRAJ,

Thanks for reaching out to us and sorry for the late reply. About your question, my area of expertise is not the safety topics, however I may be able to help you. But first I need to know if you have Safety requirements for your product, specifically regarding the recovery time for non-critical faults.

Thanks for the information

[SHIVRAJ]

Hello @alejandro_e,

Highly appreciate your help in this.

Yes, we have already derived product-specific safety requirements like the FTTI, fault handling mechanisms, operating modes, safe states, maximum voltage and current ratings, and other stuff.

The defined FTTI is 50 ms, and the FHTI we have decided is anywhere less than FTTI (<50 ms).

Looking forward to your response on the Timeout period.

Thanks in advance!

[alejandro_e]

Hello @SHIVRAJ,

This is only a personal recommendation, you will need to validate the performance of your product under the correct conditions.

Considering anything less than 50ms to be correct, I would use 2,000,000 ticks, this is, with a 48MHz clock, a little over 41ms for the recovery timeout. 

Please considere that this value will depend on how you decide to handle the faults and how to recover them. 

Let me know if this information was useful.