Calculate Interrupt Latency of FreeRTOS with LPC23xx

Jul 24, 2008 5 Replies
L

Hi guys,



i'm a student of University of Genoa (Italy). I'm new on your website an i have already found some important information for my research. You ar very cool and professional. Now i write here because i want to try to calculate the Interrupt Latenc for freeRTOS using an ARM LPC23xx.



The idea that i have is that: i want to generate an interrupt from extern and to misure the time tha will be between when i generate the interrupt and the time when the firs instruction af the interrupt routine will be executed. The misuremen should be made by inserting two probes of an oscilloscope in the interrup line and in the output. Then the time that should be between the two puls will be the Interrupt Latency.



THE PROBLEM CORE IS THE CODE!!!



So, i ask you if someone has ever wrote a code to make this or has eve made a code to calculate Interrupt Latency in some way.



Best Reguards to you all. Thanks. Davide.


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J

Yep. That's a fool proof way to measure interrupt latency. I've done it that way many times. It's a good exercise to do with any embedded system. Sometimes you don't always get the response time you require and if you don't measure it, you'll never know for sure.

JJS

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D

It also helps if you have a scope or logic analyzer at your disposal that can trigger if the response time exceeds a certain value. If the interrupt latency always stays below that threshold the scope should never trigger.

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L

OK! Thanks a lot to all!

I have calculate the researched time with the ROTS IAR PowerPac and it is very short.

Now the question is: HOW CAN I REGISTER AN APPLICATION ON THE VIC? Which are the function in FreeRTOS that handle the interrupts?

Thanks. Bye. Davide.

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L

HELP! HELP! HELP!

Have someone an example of using interrupts in FreeRTOS?

Thanks a lot! Davide.

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F

There are plenty in the FreeRTOS.org download - at least two for every port. There is also not just one way of doing it.

Write to me directly and I can help you. r ***dot*** barry [_at_] freertos.org.

Regards, Richard. + http://www.FreeRTOS.org & http://www.FreeRTOS.org/shop 17 official architecture ports, more than 6000 downloads per month. + http://www.SafeRTOS.com Certified by TÜV as meeting the requirements for safety related systems.
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