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Nested interrupt

Timer1 ISR _______________________________________________________________ | | | |___________

Timer 3 ISR _________ _________ ________ _________ ________ | | | | | | | | | | |_____| |_____| |______| |_____| |

I am using TMS320F2812 microcontroller. i need to implement the timer 3 ISR are executed within Timer 1 ISR. Is it possible to implement the same?

Any one can you please help me for that.

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Reply to
thiru_vid
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A dual core? An FPGA? Otherwise, as described, I don't see it as possible. If Timer3 preempts Timer1, leaving 0.5 usec out of every 2.0 usec available for Timer1 (not counting overhead), then Timer1's task will take 32 usec to complete a single calculation. QED SOL.

--
Rich Webb     Norfolk, VA
Reply to
Rich Webb

=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 | =A0 =A0 =A0 =A0 =A0

=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 |___________ =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0

=A0 =A0 =A0 ________

=A0 =A0| =A0 =A0 =A0 =A0 | =A0 =A0 | =A0 =A0 =A0 =A0 =A0 =A0| =A0 =A0|_____= | =A0 =A0 =A0 =A0 |_____| =A0 =A0 =A0

it

But, if there is no preemption, then it should be feasible as Timer3 occurs every 2 us while Timer1 occurs only every 10us. But, i wonder how it will be able to function when it is in the

5th interval because during that scenario/occassion, timer3 and timer1 will both be trying to get executed and some kind of racing might happen . Any ideas ?

Karthik Balaguru

Reply to
karthikbalaguru

Yes

Use software interrupt priority.

You must use Software Prioritized Interrupt PIE Block Specific Support Files.

Read SPRC097.

Reply to
Geek

               
 |_____|         |_____|      

If there is no preemption, then Timer3 won't be executed within Timer1. If there is, Timer1 won't complete its 8 usecs of calculations before the Timer1 interrupt fires again. One or the other, not both.

--
Rich Webb     Norfolk, VA
Reply to
Rich Webb

               
 |_____|         |_____|      

No, as described, Timer1 takes 80% CPU time (8us every 10us), and Timer3 takes 75% CPU Time (1.5 every 2). Those add up to more than 100%.

Reply to
Arlet

=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 | =A0 =A0 =A0 =A0 =A0

=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 |___________ =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0

_ =A0 =A0 =A0 ________

=A0 =A0 =A0| =A0 =A0 =A0 =A0 | =A0 =A0 | =A0 =A0 =A0 =A0 =A0 =A0| =A0 =A0|_= ____| =A0 =A0 =A0 =A0 |_____| =A0 =A0 =A0

Is it

Hmm,Agreed. Did not notice that even though the processing time of timer3 is 1.5us only, the timer3 occurs every 2us.

Karthik Balaguru

Reply to
karthikbalaguru

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