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Interrupts priority

Question asked by dida.martin on Nov 13, 2012
Latest reply on Nov 13, 2012 by dida.martin
Hi all

Can higher priority interrupt interrupts lower priority in his execution? For example. When I am servicing DMA ISR routine with priority 0x01 and EXTI interruption with priority 0x00 if and only if happens. Does it preempt lower priority level ISR immediately or after finishing of that routine.
While what I know just SysTick timer does it when it has higher priority then peripheral priority.
But between two priorities like DMA and EXTI it was not successful when one of them was higher why?

Next one question. I debug my applications with ST-link debugger on STM32F0 discovery board. In my one application I use ordinary delay functions from Discovery tutorial, and decrement TimingDelay variable through SysTick handler. That delay function is used in DMA ISR routine (SysTick interrupt has higher priority than DMA priority). But the problem is that.
When I use higher optimization than Level 0 in uVision studio in "Option for Target" - "C/C++" bookmark, so it creates endless loop in this part of code "while(TimingDelay != 0);" even though the variable TimingDelay is already zero value. When I use optimization Level 0 everything works fine. I don't understand why?


Thanks for your help.

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