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Why the imx6sx snvs rtc can't keep value

Question asked by huang yong on Mar 25, 2020
Latest reply on Mar 25, 2020 by Yuri Muhin

Hi

    We have a board of I.MX6sx which running Linux. We use the internal snvs rtc.

    We find that when the board power off, the rtc value can't keep, it becomes zero.We add the log in rtc read and write function in rtc-snvs.c. We set the date using linux command date -s "2020-03-25";hwclock -w

    Here is the boot kernel log after shutdown the power.

......

     read lp_cnt is 0

     read lp_cnt is 0

    snvs_rtc 20cc000.snvs:snvs-rtc-lp: rtc core: registered 20cc000.snvs:snvs-r as rtc0

   ......

    read lp_cnt is 0       

     snvs_rtc 20cc000.snvs:snvs-rtc-lp: setting system clock to 1970-01-01 00:00:00 UTC (0)

 

    We measure the vdd-snvs-in which connect the button battery, it keeps the voltage 2.7v during power off.

 

     We don't know why the imx6sx internal snvs-rtc can't keep the count value, Can you help give us some advice? 

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