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Kinetis K60 and RTC operation while powered down

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Kinetis K60 and RTC operation while powered down

‎05-05-2013 08:49 AM
1,486 Views
kecart
Contributor III

Is there a way to keep the RTC operating while the processor is powered down.  The oscillator (EXTAL32) continues to run but the RTC_TSR register is not updated.  When the board is powered up, it still has the time value that it had when it was powered down.  I am trying to get it to function as a battery backed RTC should and continue to keep the time updating while the other parts of the CPU are powered down or in reset.

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‎05-17-2013 03:41 AM
1,056 Views
kecart
Contributor III

The actual problem that was preventing the RTC from operating properly was accidentally installing the resistor across the crystal.  Removing the resistor got the RTC running as expected.  Lesson of the day, RTFM and don't install capacitors or resistor on the 32KHz clock crystal circuit.

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‎05-05-2013 06:28 PM
1,056 Views
Paul_Tian
NXP Employee
NXP Employee

Hi, Kelly

Yes, K60 provide a VBAT pin which can provide power to RTC module. This pin is used for backup battery supply for RTC and VBAT register file. So if you keep the power on VBAT pin, the RTC will continue.

Hope my reply can help you.

Best Regards

Paul

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