CODEWITHSUNDEEP
c++armgpio
user3536692
user3536692

Reputation: 137

Handle GPIO Button event with C++

Hi guys I need some help. I am making a c++ embedded application in an ARM. I need to get a push button event, I was looking for in internet and I find that the best way to do it is with interruptions. I know that I can set one pin through terminal like this "echo raise > /sys/.../gpio/gpio81/edge". But I need to know how can I get the interrupt from my C++ application when it happend, I just need some example, because I do not know if I have to use some special library.

Thank you guys I hope someone can help me.

Upvotes: 2

Views: 4960

Answers (2)

user3536692
user3536692

Reputation: 137

Hi guys I find the solution what I just wanted is here:

https://developer.ridgerun.com/wiki/index.php/Gpio-int-test.c

Thank you anyways

Upvotes: 2

Martin James
Martin James

Reputation: 24847

Manual 'mechanical' pushbuttons require debouncing. That, and the fact that pushing buttons does not require high I/O performance, means that a GPIO interrupt is an awkward overkill. It can' of course, be done, but it's easier and safer to poll the GPIO port with a timer interrupt, storing the state of the inputs and comparing with the previous state/s. If a GPIO line has changed state for a sufficient number of samples, you have your button event and can act on it.

If you are using a tasking OS, you could hook the existing timer interrupt - it's only a few instructions to handle the GPIO poll so you should not see any noticeable performace hit. If is is decided that the button/s have been pressed/released, you can signal a semaphore so that a waiting thread can quickly process the event.

Upvotes: 3

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