i.MX RT 1170 Clock Gate for OTFAD

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i.MX RT 1170 Clock Gate for OTFAD

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mjbcswitzerland
Specialist V

Hi All

I need to use the i.MX RT 1170's OTFAD to encrypt AES128 data (as I have done before on the i.MX RT 1011).

On the i.MX RT 1011 I could control the clock gate to the OTFAD in the register CCM_CCGR2 (0x00003000) but I haven't been able to find a clock gate to control it in the LPCGx registers of the i.MX RT 1070.

Does this means that it is always clocked or does it mean that it can't be enabled when on-the-fly decryption is not in use?

Regards

Mark

 

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FelipeGarcia
NXP Employee
NXP Employee

Hi Mark,

As far as I know there is no independent clock for OTFAD as it is the same as FlexSPI clock, I checked OTFAD example in RT1010 SDK and this is mentioned as well in the OTFAD_Init function, also I checked CCM_CCGR2 register in RM and did not find any register specifically for clock gating OTFAD module.

In application note below it is mentioned that OTFAD is a submodule of FlexSPI so any measurements are done based on FlexSPI clock so similar as above will apply to RT1170.

https://www.nxp.com/docs/en/application-note/AN13198.pdf

Best regards,

Felipe

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FelipeGarcia
NXP Employee
NXP Employee

Hi Mark,

As far as I know there is no independent clock for OTFAD as it is the same as FlexSPI clock, I checked OTFAD example in RT1010 SDK and this is mentioned as well in the OTFAD_Init function, also I checked CCM_CCGR2 register in RM and did not find any register specifically for clock gating OTFAD module.

In application note below it is mentioned that OTFAD is a submodule of FlexSPI so any measurements are done based on FlexSPI clock so similar as above will apply to RT1170.

https://www.nxp.com/docs/en/application-note/AN13198.pdf

Best regards,

Felipe

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- We are following threads for 7 weeks after the last post, later replies are ignored. Please open a new thread and refer to the closed one, if you have a related question at a later point in time. 

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mjbcswitzerland
Specialist V

Hello Filipe

I am sorry but I made a mistake - in my use of BEE and OTFAD in the past it was necessary to gate the clock to the OCOPT module so that the AES key source could first be selected and I confused this gate with an OCFAD gate (therefore there is no gate for OTFAD - also not in the 1011).
Since when using the technique on the BEE module (1015, 102x, 105x, 106x) it is necessary to gate the BEE clock and the OCOPT clocks I incorrectly thought I needed to find the OTFAD gate, which was my mistake.

Thanks for clarifying, which made be realise the error.

 

I note that there are presently no OTFAD usage example in the SDK though and, since the reference manual doesn't give any details, I am trying reverse engineer its usage via other means. This I managed to do on the 1011 due to very old documents still available on the Internet from old chips with the same module but it may be nice to have access to the documents one day to make life somewhat easier. I don't have any FAE anymore to help on such (although I am a customer with tens of thousands of devices on order). Do you know of any other route?

Regards

Mark

 

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