SPRUJ53B April 2024 – September 2024 TMS320F28P550SJ , TMS320F28P559SJ-Q1
Inside the interrupt service routine (ISR), the user must clear the event flag using the EVT_CLR register and then acknowledge the CPU interrupt.
If the one event occurs multiple times before the corresponding bit is cleared by software, no new interrupt is generated.
If multiple events occur simultaneously, or very close in time, it is possible to handle multiple conditions within a single interrupt. Each flag is independently set by hardware and must be cleared by application software. If multiple different events occur, the ISR can handle each in whatever order is deemed necessary by the application. It is not advisable to clear the full interrupt status register in every ISR. This can cause the application to miss events that can be detrimental to the application. A sample sequence for handling interrupts on the receiver follows; the transmitter routine is similar.
There is a chance that another event occurred during the just-handled ISR since only the snapshot of events was handled and then cleared; an event flag can still be set at the end of the ISR. As soon as the ISR completes, a new interrupt is generated and this flag is still set and can be handled accordingly.
Software accesses tied to multiple events and handled within the same ISR can cause race conditions that cause the software to not function as desired. For example, it is recommended to use different interrupt lines if the user wants to enable events for both ping and data frames. If both events are handled within the same interrupt line, the software can only respond to one of the events if both events occur close in time.