I am working with 9S08GT32 controller where part of the time my code goes into Stop 3 mode and part of the time the code is in RUN, Wait mode. I am using internal 1kHz clock generator for RTI interrupts. Normally in Run/Wait modes I am working in FEI ICG mode with Bus Clock of 15.552MHz and upon entrance to Stop3 mode, I am going to SCM ICG mode, lowering clock frequency. After receiving an RTI interrupt and terminating Stop 3 mode, the code is returning back to FEI mode. The RTI interrupt routine clears the RTIF flag (by RTIACK), and the SPMSC2_PPDF flag (by SPMSC2_PPDACK). Anyway after exit from Stop3 the RTI interrupts do stop. (In running mode or wait mode) and resume only upon entrance back to Stop 3 mode. What could be a reason for this phenomenon that RTI is not interrupting in the Run/Wait mode? Additional input is that while in BDM mode (background debug mode) the RTI interrupts do not arrive too. I have to simulate their arrival, through the debugging session.