Interrupt triggering

[dimitrissideris]

Hi there,

I am trying to handle some ADC interrupts but i have a more general question. I will try to explain my use case and use it as an example for the bigger picture.

I am using an lpcxpresso 4367 mounted on a custom pcb.

I am using an analog PIR sensor so that i can catch different levels of motion and generate the appropriate interrupts as well.

So i used lpcopen periph adc example as a code base.

Inside adc example there is ADC0_IRQHandler function which is triggered every time a specific adc channel asserts some voltage.

I want to find out (but arm specifciation only says about level and edge sensitive interrupts) when an interrupt is triggered. When ADC0_IRQHandler in my example is called?

Can i change the sensitivity of the triggering of an interrupt?

Again, in my example when no motion is detected the pir sensor generates mV that i dont care about.

Can i somehow filter values that are too low and trigger interrupt under a given threshold?

How do in general nvic interrupt handlers work? Where is their threshold specified?

Thanks a lot in advance

[jeremyzhou]

Hi Dimitris Sideris,

Thank you for your interest in NXP Semiconductor products and the opportunity to serve you.

I'd highly recommend you refer to Chapter 47： LPC43xx/LPC43Sxx 10-bit ADC0/1 in the UM10503 which has illustrates the ADC operations in details, I think it can clarify you queries.
Have a great day,
Ping

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[dimitrissideris]

I surely checked the file you mentioned. It is the first thing I check. I didn't find anything that clears up my questions.

Can you please refer to it more specifically?

Thanks!

[jeremyzhou]

Hi Dimitris Sideris,,

Thanks for your reply.

1. Can I change the sensitivity of the triggering of an interrupt?

Now, the ADC can support to select the trigger source (See Fig 1).

                                                                       Fig 1

2. Can I somehow filter values that are too low and trigger interrupt under a given threshold?

The ADC doesn't support the feature.

3. How do in general nvic interrupt handlers work? Where is their threshold specified?

About the NVIC, please refer to the Chapter 9 for details in the reference manual: UM10503.

Hope this is clear.
Have a great day,
Ping

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