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Does the NVIC really do interrupt nesting?

Note: This was originally posted on 23rd February 2011 at http://forums.arm.com

For days I've been banging my head with a problem that shouldn't take more than a minute time otherwise. How to get the NVIC of Cortex M3 handle the simplest in the world interrupt nesting - an interrupt within interrupt.
In details - I have the SysTick running that executes my handling function. What I am trying to achieve is to re-enable the SysTick interrupt and let the same function be executed should another SysTick has occured while it was still serving the previous one. With the old "dumb" ARM7's VIC that was the easiest thing to do - just enabling the interrupts again once I've entered my function. But with this "advanced" one, a person apparently has to go through some tricks to get the job done.
Any help would be warmly welcome!
Thanks

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Joseph Yiu over 11 years ago

Note: This was originally posted on 24th February 2011 at http://forums.arm.com

NVIC supports nested interrupts, but the nesting can only occur if the new interrupt has higher priority than the executing one. Also, Cortex-M3 does not allow reentrant of interrupt (if a interrupt is already in active state, it cannot enter it again until the active status is cleared.)

Your question has been asked before in various forums, some pointers here:
http://forums.arm.com/index.php?/topic/14393-reentrant-interrupt-on-systick-with-the-cortex-m3/
http://forums.arm.com/index.php?/topic/12745-abort-some-questions-of-arm-interrupt/
http://e2e.ti.com/support/microcontrollers/stellaris_arm_cortex-m3_microcontroller/f/471/p/59877/220223.aspx?PageIndex=2

Google for reentrant interrupt on Cortex-M3 you can find more.
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Joseph Yiu over 11 years ago

Note: This was originally posted on 24th February 2011 at http://forums.arm.com

NVIC supports nested interrupts, but the nesting can only occur if the new interrupt has higher priority than the executing one. Also, Cortex-M3 does not allow reentrant of interrupt (if a interrupt is already in active state, it cannot enter it again until the active status is cleared.)

Your question has been asked before in various forums, some pointers here:
http://forums.arm.com/index.php?/topic/14393-reentrant-interrupt-on-systick-with-the-cortex-m3/
http://forums.arm.com/index.php?/topic/12745-abort-some-questions-of-arm-interrupt/
http://e2e.ti.com/support/microcontrollers/stellaris_arm_cortex-m3_microcontroller/f/471/p/59877/220223.aspx?PageIndex=2

Google for reentrant interrupt on Cortex-M3 you can find more.
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