IMX6UL RTC is clock getting reset after power cycle

[theats]

Hello,

I am using an IMX6UL processor.

I am trying to set up an RTC which I can use during the power cycles to find how long the power was off.

At present, I am using SNVS_HP RTC, which is working fine when the power is ON.

Once the power cycle occurs the value of the RTC gets reset and it starts from zero again.

I have read the datasheet and I saw we can use SNVS_HP and SNVS_LP.

But, I did not understand the difference between them, I have few questions can any please answer and help me to understand. 

Difference between SNVS_HP and  SNVS_LP and SNVS_LP_MC?

Will SNVS_HP will be active after power off for few seconds based on the power supply of battery cell?

Can I use SNVS_HP during the power cycle for finding the power-off time?

I have seen some of the examples in other imx processors where SNVS_LP is used during power loss, but the datasheet does not give information on this, it does not give information on whether we can use SNVS LP as normal RTC during power cycles?.

The datasheet gives only information SNVS_LP_MC registers. Seeing this I get doubt whether im6ul supports normal SNVS_LP or not.

So, can we use SNVS_LP as normal RTC not as SNVS_LP_MC during the power cycle?

As there is no direct register to use SNVS_LP as normal RTC, can we acesse SNVS_LP using SNVS_HP during the power cycle?

Thank you.

[igorpadykov]

Hi Amit

difference between SNVS_HP and SNVS_LP is described below:

 

Best regards
igor

[theats]

Hi,

Thanks for your reply.

I understood this part.

My another question was whether can I use SNVS_LP as a normal RTC even after power off  ?

Because, as per my understanding the reference manual states that SNVS_LP can be used with Monotonic Counter (LP-MC).

I also can not see any register to use SNVS_LP as simple RTC clock similar to SNVS_HP.

And we can not reload LP-MC, also as understood it is not useful as normal timer to find out the time during power loss. 

Actually, I am new to this topic of SNVS_RTC and I am having a confusion that does imx6ul supports a SNVS_RTC which will be running even after power loss until the battery supply lasts ?

@igorpadykov  I look forward for reply for solving my issue.

[igorpadykov]

yes  SNVS_LP can be used as normal RTC after power off provided that battery is connected

to VDD_SNVS_IN.

>does imx6ul supports a SNVS_RTC which will be running even after power loss until the battery supply lasts ?

yes

Best regards
igor

[theats]

Hi Igor,

@igorpadykov Thank you for replying very soon.

1. Do I need to use SNVS_LP-MC for using SNVS_RTC which will be running even after power loss until the battery supply lasts ?

2. If I have to use SNVS_LP_MC the what about the LP_MC rollover, will I be able to reset the rtc values normally ?

3. The SDK does not have an example for this so can I get any reference example for using SNVS_LP in imx6ul ?