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How does FreeRTOS handle the spurious int?

Posted by francis wang on August 20, 2009
Spurious interrupts are possible to occur in the ARM7TDMI based microcontroller such as the LPC2114/2124/2212/2214 due to the asynchronous interrupt handling.
So does FreeRTOS use certain method to deal with this kind of interrupts?

Besides, if I use soft I2c in a task, should I use mutex lock-unlock to invoke the i2c routine or use the enter critical - exit crital method? what is the diffence?If I use the mutex method , the i2c routine is still possibly interrupted by the hardware interrupts,isn't it?

Kindly regards!

RE: How does FreeRTOS handle the spurious int

Posted by Dave on August 20, 2009
Users should ensure that spurious interrupts are handled correctly in accordance with the documentation from the device manufacturer. For example, NXP have an ap note describing how to handle them. I think some FreeRTOS demos have handlers for these interrupts, but probably not all. Generally you just clear the interrupt then return.

You may be better posting your unrelated questions in two separate threads, that way more people will see the second question.

I would first say if you are using I2C in just one task then do you need a mutex or critical section at all? Normally they would only be used to prevent more than one task accessing the same peripheral at the same time.

RE: How does FreeRTOS handle the spurious int?

Posted by John W. on August 27, 2009
I usually develop what I call 'interrupt_grabber' that handles all undefined and/or unhandled IRQ's in a system - and just do a while(1); in them so I can identify what's going on in the system - just a little different way to answer your question.

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