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Kinetis K66 Hard Fault Accessing RTC in debug mode

Question asked by Emanuele Marraccini on Jan 9, 2018
Latest reply on Jan 16, 2018 by Robin_Shen

Dear All,


I'm having some problems using internal RTC module on a custom board with MK66FN2M0VMD18 processor.


I'm using KDS 3.0 IDE with GCC compiler and Segger Jlink debugger.


I use internal RTC in my program and I poll the device periodically.


If I run the board programmed everything works and the program executes with no issues.


But If I try to run the program in debug mode using jlink debugger I get an hard fault and the program halts when I attempt to access RTC device.


If I comment instructions that uses the RTC internal device the program runs with no issues too.


I've checked the K66 Sub-Family Reference Manual and I read that a bus error may be issued if the VBAT pin is not connected or if is not provided with the right voltage.


I've measured the voltage on VBAT pin and I always found 3.3V.


Do You know why the hard fault is caused by RTC device when I run the brogram through emulator? Is there some workaround to correct this issue? Any HW or SW suggestion?


All Your support is appreciated.