What is SNVS mode for RT1170 in ERR051122

[takayuki_ishii]

Hello community,

I'm checking error for RT1170 and I have some questions about errata ERR051122.

In errata ERR051122: SNVS: Some fuse trim values are lost in SNVS mode,

Q.1 What does "some fuse trim values" refer to?

Is it correct to understand that the eFuse has a value written as a threshold value to compare with voltage, clock, and temperature, but I misread this value?

It say that

"GPIO_SNVS_xx pins will automatically switch to tamper function in SNVS mode,

 even for the devices that do not support tamper and have configured the pins for their GPIO13 functions."

Q.2  Does RT1170 have SNVS mode(SNVS low power mode)?

 It have no information about SNVS mode in Reference Manual IMXRT1170RM rev1.

And application note of AN13148:I.MXRT1170 Low-Power Modes say that 

"The SNVS low-power mode is not described in this document."

In errata, Workaround: 1 is "Disable voltage, clock, and temperature tampers before entering in SNVS mode. The tampers can be re-enabled after exiting SNVS."

Q.3 What we must do disable voltage, clock and temperature tampers.

What is the specific way to disable those features?

Q4. To understand this errata, we must request and read Security Reference Manual for the i.MX RT1170 Processor IMXRT1170SRM?

Best regards,

Ishii.

[jingpan · Accepted solution]

Hi @takayuki_ishii ,

1. These values is about tamper function. If your chip doesn't support or enable the tamper function, you should only take care the GPIO_SNVS_xx.

2. Yes, RT1170 has SNVS mode. You can refer to power_mode_switch demo in SDK.

3./4. If your chip has temper function, of course you should read it.

Regards,

Jing

[takayuki_ishii]

Hello @jingpan 

Thank you for your replay.

And sorry my basic questions.

My customer plan to use RT1171, it have no tamper function.

And plan to use SNVS mode.

In this time, Errata ERR051122 must care not only tamper enable device but also no tamper device like RT1171.

Is it correct?

If so, to use GPIO_SNVS_xx in SNVS mode we must do workaround 1.

Is it correct?

We try to show power_mode_switch demo in SDK to understand how to enable SNVS mode.

Best regards,

Ishii.

[jingpan]

Hi @takayuki_ishii ,

Yes, customer must take care those pins even they plan to use RT1171.

Regards,

Jing

[takayuki_ishii]

Hello jingpan

Thank you for your quick reply.

I will tell my clients to use it with caution.

Best regards,

Ishii.