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QN908X Stack Timer/RTC FR not waking MCU from Deep Sleep (0)

Question asked by Jose Raffucci on Mar 5, 2019
Latest reply on Mar 29, 2020 by Jose Raffucci

I'm having trouble getting the RTC Free-Run interrupt to wake up the MCU when I go into DS0.   Seems to work ok when just sleeping. 


Note:  I am using a digital clock as my XTAL32K source which I suspect may be a factor.  Clock input is on pin XTAL32_IN/PB01.  XTAL32_OUT/PB02 is floating. 



I've set up a test that sets up an LP timer that toggles an led at 10Hz.  BLE is disabled and all other tasks are shut down. 





Is there anything about the architecture that would cause this behavior for a digital 32K clock source?  I'm going to switch over to use the internal oscillator to see if I can get my test to work with it next.  One thing I noticed today is that this is occurring while I have the debugger active so it may be a stack/setup issue rather than a hardware one.


The freerun timer is enabled and the interrupt and wakeup bits are set:



After a wakeup event, the reason correctly identifies that a TMR event occurred:


But the wakeup is actually coming from the BLE_LLTimer and not the TMR.  The MCU wakes up roughly every 10s and not 100ms as expected.


Any ideas on what might be going on?