Posted on May 17, 2011 at 11:54Q1. If a low priority interrupt occurs while a high/low priority interrupt service routine is running, Is the low priority interrupt that occured is lost and won't be handled after the running ISR is completed?
A1. The low priority interrupt will be serviced after the high priority ISR is serviced.
Q2. While EA=0(all interrupts disabled)and an interrupt occures,is it lost?which means does the uPSD remebers the interrupt activation and jumps to its ISR after EA is set? Is it important if the interrupt that occurs while EA=0 is a high or low priority interrupt?
A2. When EA is set to 0, NO interrupts will be acknowledged. It will not remember any interrupt being actived during EA=0.
Q3. If all interrupts are with the same priority ,does in this case servicing the interrupts is based only on the priority level chart?which means will interrupt ext0 be serviced before timer0 for example(in case both arrive at the same time)?
A3. When the requests of the same priority are received simultaneoulsy, an internal polling sequence determines which request is serviced. So within each priority level, there is a second priority structure determined by the polling sequence. Please refer to page 42 of the uPSD323x data sheet.
