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Issue with RTC: Both 24 MHz & 32 KHz Clocks are running on Powerdown

Question asked by Ankur Patel on May 5, 2014
Latest reply on May 7, 2014 by Ankur Patel

Hello Friends,


I am using custom mx28 board with 5V only supply. It has powersupply for RTC as below. Board has 32.768 KHz and 24 MHz crystal. I would like to run the RTC on power down via 32 KHz crystal instead of 24 MHz crystal.


At the U-Boot prompt, when I tried setting the HW_RTC_PERSISTENT0 register value to 0x121 (Keeping Clock source as 32 KHz and powering up xtal 32 KHz via setting bits  CLOCKSOURCE and XTAL32KHZ_PWRUP) as below:


MX28EVK U-Boot > mm 0x80056060

80056060: 00020100 ? 121


After that, I can see the Clock on 32 KHz and 24 MHz which is good. Now when I power down the board, I still see both Clocks running instead of only 32 KHz for RTC. Can anyone share some comments or concerns?


Thank you,