topic Re: i.MX6UL SNVS-LP-RTC low voltage detection in i.MX Processors

i.MX6UL SNVS-LP-RTC low voltage detection

yurirellosa — Wed, 01 Jun 2016 08:02:46 GMT

Hello

We are planning on using the on-chip RTC module of the cpu.

We are now able to make it work and retain/make the clock running during power-off via external battery.

As with normal external RTC modules, they have a "Low voltage detected" function to judge whether power was cut off from the module. When low voltage is detected you cannot trust the RTC clock values so we reset to clock values to "0"

As we would like to use the CPU's internal RTC, is there a way to judge for "low voltage" or if RTC values can be "trusted"

Thank you

Best Regards,

Yuri Rellosa

Re: i.MX6UL SNVS-LP-RTC low voltage detection

Yuri — Wed, 01 Jun 2016 08:58:35 GMT

Hello,

i.MX6 UL supports low voltage detector by the DryICE, which is only

available on the derivative G3.

Have a great day,
Yuri

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Re: i.MX6UL SNVS-LP-RTC low voltage detection

yurirellosa — Thu, 02 Jun 2016 06:32:09 GMT

Hello Yuri

Does this mean that since our i.MX6UL is a derivative G2, we have no way of knowing if the internal RTC still has a trusted value just by looking into the CPU registers?

Do you have any out-of-the-box(cpu) ways to work around this?

Best Regards,

Yuri

Re: i.MX6UL SNVS-LP-RTC low voltage detection

Yuri — Thu, 02 Jun 2016 06:35:34 GMT

Hello,

An external monitor scheme may be used for non-G3 versions.

Regards,

Yuri.

Re: i.MX6UL SNVS-LP-RTC low voltage detection

yurirellosa — Thu, 02 Jun 2016 07:01:25 GMT

Hello Yuri

Thank you for your answers.

Two last questions:

1. During CPU main power-off, if you remove the battery powering the internal RTC and put it back again,

will that restart the RTC to count up?

2. When power to RTC has been cut off, is it safe to assume that on the next CPU power-up the counter registers

will default back to 0x0000 (zero)?

Best Regards,

Yuri

Re: i.MX6UL SNVS-LP-RTC low voltage detection

Yuri — Mon, 06 Jun 2016 08:24:25 GMT

Hello,

Please look at my comments below.

> During CPU main power-off, if you remove the battery powering the internal RTC
> and put it back again, will that restart the RTC to count up?

No.

> When power to RTC has been cut off, is it safe to assume that on the next CPU power-up the
> counter registers will default back to 0x0000 (zero)?

Yes, assuming general system POR

Regards,

Yuri.