For interrupts and events, failure can be detected using information about the time behavior of the system. The monitored signals can be either periodic or aperiodic.

For a typical closed loop control application, most of the critical events are periodic in nature and these periodic events can be monitored and incoherence in the events can be used for fault detection. A few places where online monitoring periodic interrupts and events can be employed include:

• Periodic generation of ADC start of conversion (SoC) (x): ADC SoC signal can be used to generate an external interrupt (XINT) with the help of X-BAR. The occurrence of periodic interrupts can be monitored.
• Periodic DMA trigger: Some of the DMA events may also be periodic in nature (for example, copy of ADC results, updating of CMPA register, and so forth). DMA supports interrupt generation on the completion of the DMA action and this capability can be used for online monitoring.
• Periodic occurrence of ECAP and EQEP interrupts

Monitoring of interrupts and events which are normally not expected during the correct operation can also be used to improve the diagnostic coverage (for example, ECC correctable error interrupt).