My application works normally at fbus = 6.291456 MHz with FEE mode by using external 32.768kHz crystal.
I also setup and trim MCU for FEI mode to work at same bus frequency. I want to use FEI mode instead of SCM mode when any failure occurs on external 32.768 crystal while MCU in FEE mode. And if the fault on external crystal disappeared, I want to switch back to FEE mode.
In my application, clock monitor enabled and, I can detect loss of lock and loss of clock conditions.
Here is my questions:
- If I start with FEI mode, I can't switch MCU to FEE mode. I initialized mcu with "ICGC1 = 0b00101100;// FEI mode", then, MCU can't enter FEE mode with "ICGC1_CLKS=3;"
- In FEI mode, RTI interrupt loses its functionality?
- ICGS1_ERCS flag doesn't indicate external crystal status when MCU in FEI mode?
- I need events such as FEE mode is failed switch FEI and in FEI mode, FEE mode can be usable again, switch FEE.
- Can I detect external crystal failures in stop3 mode?